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Olding A, Lucas NT, Ho CC, Bissember AC. Correction: Acridine-based copper(I) PNP pincer complexes: catalysts for alkyne hydroboration and borylation of aryl halides. Dalton Trans 2024; 53:6128. [PMID: 38497132 DOI: 10.1039/d4dt90050b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Correction for 'Acridine-based copper(I) PNP pincer complexes: catalysts for alkyne hydroboration and borylation of aryl halides' by Angus Olding et al., Dalton Trans., 2024, 53, 4471-4478, https://doi.org/10.1039/D3DT04269C.
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Affiliation(s)
- Angus Olding
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia.
| | - Nigel T Lucas
- Department of Chemistry, University of Otago, Dunedin, Otago 9054, New Zealand
| | - Curtis C Ho
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia.
| | - Alex C Bissember
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia.
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2
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Olding A, Lucas NT, Ho CC, Bissember AC. Acridine-based copper(I) PNP pincer complexes: catalysts for alkyne hydroboration and borylation of aryl halides. Dalton Trans 2024; 53:4471-4478. [PMID: 38348688 DOI: 10.1039/d3dt04269c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Abstract
PNP pincers represent some of the most well-studied ligand systems in coordination chemistry owing to their high thermal and chemical stability, and the predictable metal coordination geometries of associated metal complexes. Examples of first-row transition metal complexes bearing acridine-based PNP pincer ligands are extremely rare. This study reports the preparation and structural authentication of acridine-based copper(I) PNP complexes, which reveal the profound effects that the steric bulk of methylene-tethered P-substituents has on metal centre coordination number and geometry. The capacity of these systems to mediate copper-catalysed alkyne hydroboration and the borylation of aryl halides is also investigated.
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Affiliation(s)
- Angus Olding
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia.
| | - Nigel T Lucas
- Department of Chemistry, University of Otago, Dunedin, Otago 9054, New Zealand
| | - Curtis C Ho
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia.
| | - Alex C Bissember
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia.
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3
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Tang M, Draper F, Pham LN, Ho CC, Huang H, Sun J, Thickett SC, Coote ML, Connell TU, Bissember AC. Photochemical Povarov-type Reactions: Electron Donor-Acceptor Photoactivation by Visible Light. J Org Chem 2024; 89:2683-2690. [PMID: 38314706 DOI: 10.1021/acs.joc.3c02746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
This report investigates the mechanism of photochemical Povarov-type reactions of N,N-dialkylanilines and maleimides in polar solvents (DMF or dioxane) in the presence of light. Fundamental aspects of the electron donor-acceptor (EDA) photoactivation pathway proposed to underpin this chemistry are examined through integrated experimental and computational studies. This approach provided evidence supporting the involvement of an EDA complex in facilitating this chemistry via a reaction mechanism that does not involve a triplet manifold. Most notably, our findings indicate that relying solely on UV-vis absorption spectroscopic data to either account for or predict reactivity in synthetic experiments may not always provide the complete picture. More specifically, this relates to considering UV-vis absorption spectroscopic data, calculated values for association constants (KEDA) and molar extinction coefficients (ε), with the reactivity observed in associated synthetic reactions in practice.
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Affiliation(s)
- Meiqiong Tang
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Felicity Draper
- School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3220, Australia
| | - Le Nhan Pham
- Institute for Nanoscale Science and Technology, Flinders University, Adelaide, South Australia 5042, Australia
| | - Curtis C Ho
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Hai Huang
- Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China
| | - Jianwei Sun
- Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University, Changzhou 213164, China
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Stuart C Thickett
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Michelle L Coote
- Institute for Nanoscale Science and Technology, Flinders University, Adelaide, South Australia 5042, Australia
| | - Timothy U Connell
- School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3220, Australia
| | - Alex C Bissember
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
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4
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Shiri F, Ho CC, Bissember AC, Ariafard A. Advancing Gold Redox Catalysis: Mechanistic Insights, Nucleophilicity-Guided Transmetalation, and Predictive Frameworks for the Oxidation of Aryl Gold(I) Complexes. Chemistry 2024; 30:e202302990. [PMID: 37967304 DOI: 10.1002/chem.202302990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Indexed: 11/17/2023]
Abstract
Gold redox catalysis, often facilitated by hypervalent iodine(III) reagents, offers unique reactivity but its progress is mainly hindered by an incomplete mechanistic understanding. In this study, we investigated the reaction between the gold(I) complexes [(aryl)Au(PR3 )] and the hypervalent iodine(III) reagent PhICl2 , both experimentally and computationally and provided an explanation for the formation of divergent products as the ligands bonded to the gold(I) center change. We tackled this essential question by uncovering an intriguing transmetalation mechanism that takes place between gold(I) and gold(III) complexes. We found that the ease of transmetalation is governed by the nucleophilicity of the gold(I) complex, [(aryl)Au(PR3 )], with greater nucleophilicity leading to a lower activation energy barrier. Remarkably, transmetalation is mainly controlled by a single orbital - the gold dx 2 -y 2 orbital. This orbital also has a profound influence on the reactivity of the oxidative addition step. In this way, the fundamental mechanistic basis of divergent outcomes in reactions of aryl gold(I) complexes with PhICl2 was established and these observations are reconciled from first principles. The theoretical model developed in this study provides a conceptual framework for anticipating the outcomes of reactions involving [(aryl)Au(PR3 )] with PhICl2 , thereby establishing a solid foundation for further advancements in this field.
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Affiliation(s)
- Farshad Shiri
- Department of Chemistry, Islamic Azad University, Central Tehran Branch, Poonak, Tehran, Iran
| | - Curtis C Ho
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Alex C Bissember
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Alireza Ariafard
- Research School of Chemistry, Australian National University, Canberra, ACT, 2601, Australia
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5
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Zarfos SD, Deans BJ, Ho CC, Jordan GJ, Smith JA, Bissember AC. Distinctive Arbutin-Containing Markers: Chemotaxonomic Significance and Insights into the Evolution of Proteaceae Phytochemistry. Chem Biodivers 2023; 20:e202301112. [PMID: 37726205 DOI: 10.1002/cbdv.202301112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 09/17/2023] [Accepted: 09/19/2023] [Indexed: 09/21/2023]
Abstract
Natural products isolation studies of eight endemic Tasmanian Proteaceae species - Agastachys odorata, Persoonia juniperina, Hakea megadenia, Hakea epiglottis, Orites diversifolius, Orites acicularis, Orites revolutus, and Telopea truncata - and three endemic Australian Proteaceae species Banksia serrata, Banksia praemorsa, and Banksia marginata were undertaken. Two previously unreported glycoside-derived natural products were identified, in addition to four other tremendously rare arbutin esters. The results of this study provide further evidence consistent with the proposal that these distinctive arbutin esters represent markers that can provide valuable insights into the chemical evolution of plant species within the family Proteaceae.
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Affiliation(s)
- Samuel D Zarfos
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Bianca J Deans
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Curtis C Ho
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Gregory J Jordan
- School of Natural Sciences - Biological Sciences, University of Tasmania, Hobart, 7001, Tasmania, Australia
| | - Jason A Smith
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Alex C Bissember
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia
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6
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Gyeltshen T, Deans BJ, Ho CC, Kilah NL, Smith JA, Bissember AC. Furanosesquiterpenes and Related Natural Products from Myoporum Species: Isolation and Semisynthesis. J Nat Prod 2023; 86:1584-1595. [PMID: 37262439 DOI: 10.1021/acs.jnatprod.3c00278] [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] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Myoporum species are recognized as toxic plants. Essential oils from the leaves of these species contain furanosesquiterpenes, which comprise the active toxins. In this report, natural products isolation studies of three Myoporum species (M. insulare, M. parvifolium, and M. montanum) afforded two previously unreported furanosesquiterpenes (24 and 25) and three unprecedented γ-lactone-containing analogues (26-28), along with nine previously reported furanosesquiterpenes and five other natural products. Among the 14 furanosesquiterpenes and related compounds isolated in this study, we observed three distinct types of furanosesquiterpene structures isolated from each of these Myoporum species. Semisyntheses of four sesquiterpene natural products were completed from (-)-ngaione over two steps in each case. This included the synthesis of the lactam-containing sesquiterpene myoporumine A.
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Affiliation(s)
- Thinley Gyeltshen
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Bianca J Deans
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Curtis C Ho
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Nathan L Kilah
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Jason A Smith
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Alex C Bissember
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
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7
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Olding A, Ho CC, Lucas NT, Bissember AC. Pretransmetalation Intermediates in Suzuki-Miyaura Cross-Couplings: Synthesis of C sp3-, C sp2- and C sp-Organopalladium(II) Boronates. Inorg Chem 2023; 62:5054-5057. [PMID: 36946982 DOI: 10.1021/acs.inorgchem.3c00198] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
Organopalladium(II) boronates represent fundamental pretransmetalation intermediates in Suzuki-Miyaura cross-couplings. These species are typically kinetically unstable, making them particularly elusive. In this study, a range of unprecedented, kinetically stable alkyl-, alkenyl-, allenyl-, and alkynylpalladium(II) boronates were prepared from various Csp3, Csp2, and Csp electrophiles via a simple, general method. The structures of these complexes were secured by X-ray crystallography, and the chemical competence of a number of these intermediates in transmetalation was demonstrated.
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Affiliation(s)
- Angus Olding
- School of Natural Sciences─Chemistry, University of Tasmania (UTAS), Hobart, Tasmania 7001, Australia
| | - Curtis C Ho
- School of Natural Sciences─Chemistry, University of Tasmania (UTAS), Hobart, Tasmania 7001, Australia
| | - Nigel T Lucas
- Department of Chemistry, University of Otago, Dunedin, Otago 9054, New Zealand
| | - Alex C Bissember
- School of Natural Sciences─Chemistry, University of Tasmania (UTAS), Hobart, Tasmania 7001, Australia
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8
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Olding A, Ho CC, Lucas NT, Canty AJ, Bissember AC. Pretransmetalation Intermediates in Suzuki–Miyaura C–C and Carbonylative Cross-Couplings: Synthesis and Structural Authentication of Aryl- and Aroylnickel(II) Boronates. ACS Catal 2023. [DOI: 10.1021/acscatal.2c05657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Affiliation(s)
- Angus Olding
- School of Natural Sciences−Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Curtis C. Ho
- School of Natural Sciences−Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Nigel T. Lucas
- Department of Chemistry, University of Otago, Dunedin, Otago 9054, New Zealand
| | - Allan J. Canty
- School of Natural Sciences−Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Alex C. Bissember
- School of Natural Sciences−Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
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9
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Olding A, Ho CC, Maiti D, Bissember AC. Structural authentication of intermediates of mechanistic significance in palladium- and nickel-catalysed cross-couplings: case studies. Chem Commun (Camb) 2023; 59:5144-5155. [PMID: 37039067 DOI: 10.1039/d3cc00882g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
Abstract
This article examines a selection of case studies that highlight key strategies that have enabled the structural authentication of important species that shed light on fundamental on-cycle intermediates in palladium-...
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Affiliation(s)
- Angus Olding
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia.
| | - Curtis C Ho
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia.
| | - Debabrata Maiti
- Department of Chemistry, IIT Bombay, Powai, Mumbai 400076, India
| | - Alex C Bissember
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania, 7001, Australia.
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10
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Smith J, Hyland IK, Ho CC, Vuong D, Tsai YA, Lacey E, Bissember AC. Synthesis of 4-phenylthienoquinolines via Suzuki–Miyaura cross-couplings. ARKIVOC 2022. [DOI: 10.24820/ark.5550190.p011.813] [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: 11/23/2022] Open
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11
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Poland EM, Ho CC. Photoactive N‐Heterocyclic Carbene Transition Metal Complexes in Bond‐Forming Photocatalysis: State‐of‐the‐Art and Opportunities. Appl Organomet Chem 2022. [DOI: 10.1002/aoc.6746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Eve M. Poland
- School of Natural Sciences – Chemistry University of Tasmania Hobart Tasmania Australia
| | - Curtis C. Ho
- School of Natural Sciences – Chemistry University of Tasmania Hobart Tasmania Australia
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12
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Tang M, Cameron L, Poland EM, Yu LJ, Moggach SA, Fuller RO, Huang H, Sun J, Thickett SC, Massi M, Coote ML, Ho CC, Bissember AC. Photoactive Metal Carbonyl Complexes Bearing N-Heterocyclic Carbene Ligands: Synthesis, Characterization, and Viability as Photoredox Catalysts. Inorg Chem 2022; 61:1888-1898. [PMID: 35025492 DOI: 10.1021/acs.inorgchem.1c02964] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This report details the synthesis and characterization of a small family of previously unreported, structurally related chromium, molybdenum, tungsten, manganese, and iron complexes bearing N-heterocyclic carbene and carbonyl supporting ligands. These complexes have the general form [ML(CO)3X] or [ML(CO)3], where X = CO or Br and L = 1-phenyl-3-(2-pyridyl)imidazolin-2-ylidene. Where possible, the solid-state, spectroscopic, electrochemical, and photophysical properties of these molecules were studied using a combination of experiment and theory. Photophysical studies reveal that decarbonylation occurs when these complexes are exposed to ultraviolet light, with the CO ligand being replaced with a labile acetonitrile solvent molecule. To obtain insights into the potential utility, scope, and applications of these complexes in visible-light-mediated photoredox catalysis, their capacity to facilitate a range of photoinduced reactions via the reductive or oxidative functionalization of organic molecules was investigated. These chromium, molybdenum, and manganese catalysts efficiently facilitated atom-transfer radical addition processes. In light of their photolability, these types of catalysts may potentially allow for the development of photoinduced reactions involving less conventional inner-sphere electron-transfer pathways.
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Affiliation(s)
- Meiqiong Tang
- School of Natural Sciences-Chemistry, University of Tasmania (UTAS), Hobart, Tasmania7001, Australia
| | - Lee Cameron
- School of Molecular and Life Sciences, Curtin University, Perth, Western Australia6102, Australia
| | - Eve M Poland
- School of Natural Sciences-Chemistry, University of Tasmania (UTAS), Hobart, Tasmania7001, Australia
| | - Li-Juan Yu
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory2601, Australia
| | - Stephen A Moggach
- School of Molecular Sciences, University of Western Australia, Perth, Western Australia6009, Australia
| | - Rebecca O Fuller
- School of Natural Sciences-Chemistry, University of Tasmania (UTAS), Hobart, Tasmania7001, Australia
| | - Hai Huang
- Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology, School of Petrochemical Engineering, Changzhou University, Changzhou213164, China
| | - Jianwei Sun
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, SAR, China
| | - Stuart C Thickett
- School of Natural Sciences-Chemistry, University of Tasmania (UTAS), Hobart, Tasmania7001, Australia
| | - Massimiliano Massi
- School of Molecular and Life Sciences, Curtin University, Perth, Western Australia6102, Australia
| | - Michelle L Coote
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory2601, Australia
| | - Curtis C Ho
- School of Natural Sciences-Chemistry, University of Tasmania (UTAS), Hobart, Tasmania7001, Australia
| | - Alex C Bissember
- School of Natural Sciences-Chemistry, University of Tasmania (UTAS), Hobart, Tasmania7001, Australia
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13
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Vanston CR, Nicholls TP, Bissember AC, Gardiner MG, Ho CC. Cationic Charge-Appended Abnormal Carbenes: Synthesis and Study of Electronically Modified Abnormal N-Heterocyclic Carbenes. Inorg Chem 2021; 61:622-632. [PMID: 34941242 DOI: 10.1021/acs.inorgchem.1c03336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A range of palladium complexes featuring electronically modified, imidazole-based abnormal N-heterocyclic carbene (aNHC) ligands have been prepared in the hopes of accessing a new class of cationic aNHC ligands electronically distinct from normal NHCs and aNHCs. These palladium complexes represent the first examples of transition metal-ligated aNHC complexes featuring a cationic moiety adjacent to the abnormal carbene center. It was anticipated that these design principles could facilitate electron transfer between the imidazolinylidene and the cationic heterocycle, thus reducing the electron density at the abnormal carbene center. However, this case study suggests that greater conformational restrictions that allow for heterocycle coplanarity are necessary to achieve significant electron transfer and enable access to a new class of cationic charge-appended aNHCs with unique electronic properties.
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Affiliation(s)
- Catriona R Vanston
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Thomas P Nicholls
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Alex C Bissember
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Michael G Gardiner
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Curtis C Ho
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
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Olding A, Ho CC, Canty AJ, Lucas NT, Horne J, Bissember AC. Synthesis of Arylpalladium(II) Boronates: Confirming the Structure and Chemical Competence of Pre‐transmetalation Intermediates in the Suzuki–Miyaura Reaction. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202104802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Angus Olding
- School of Natural Sciences—Chemistry University of Tasmania Hobart Tasmania Australia
| | - Curtis C. Ho
- School of Natural Sciences—Chemistry University of Tasmania Hobart Tasmania Australia
| | - Allan J. Canty
- School of Natural Sciences—Chemistry University of Tasmania Hobart Tasmania Australia
| | - Nigel T. Lucas
- Department of Chemistry University of Otago Dunedin, Otago New Zealand
| | - James Horne
- Central Science Laboratory University of Tasmania Hobart Tasmania Australia
| | - Alex C. Bissember
- School of Natural Sciences—Chemistry University of Tasmania Hobart Tasmania Australia
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15
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Olding A, Ho CC, Canty AJ, Lucas NT, Horne J, Bissember AC. Synthesis of Arylpalladium(II) Boronates: Confirming the Structure and Chemical Competence of Pre-transmetalation Intermediates in the Suzuki-Miyaura Reaction. Angew Chem Int Ed Engl 2021; 60:14897-14901. [PMID: 33890395 DOI: 10.1002/anie.202104802] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Indexed: 11/10/2022]
Abstract
Palladium(II) boronates are recognized as fundamental pre-transmetalation intermediates in Suzuki-Miyaura cross-couplings. While these typically transient species have been detected and studied spectroscopically, it is conspicuous that they have never been isolated since this important reaction was discovered over forty years ago. This study reports the synthesis of a family of unprecedented arylpalladium(II) boronates that are, by design, kinetically stable at ambient temperature, both in solution and in the solid state. These properties enabled unambiguous crystallographic confirmation of their structure for the first time and their chemical competence in a Suzuki-Miyaura reaction was demonstrated.
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Affiliation(s)
- Angus Olding
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania, Australia
| | - Curtis C Ho
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania, Australia
| | - Allan J Canty
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania, Australia
| | - Nigel T Lucas
- Department of Chemistry, University of Otago, Dunedin, Otago, New Zealand
| | - James Horne
- Central Science Laboratory, University of Tasmania, Hobart, Tasmania, Australia
| | - Alex C Bissember
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania, Australia
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16
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Yang B, Wong YS, Lam WW, Geng H, Huang CY, Tang KK, Law WK, Ho CC, Nam PH, Cheung KY, Yu SK. Initial clinical experience of patient-specific QA of treatment delivery in online adaptive radiotherapy using a 1.5 T MR-Linac. Biomed Phys Eng Express 2021; 7. [PMID: 33882471 DOI: 10.1088/2057-1976/abfa80] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 04/21/2021] [Indexed: 11/11/2022]
Abstract
Purpose. This study aims to evaluate the performance of a commercial 1.5 T MR-Linac by analyzing its patient-specific quality assurance (QA) data collected during one full year of clinical operation.Methods and Materials. The patient-specific QA system consisted of offline delivery QA (DQA) and online calculation-based QA. Offline DQA was based on ArcCHECK-MR combined with an ionization chamber. Online QA was performed using RadCalc that calculated and compared the point dose calculation with the treatment planning system (TPS). A total of 24 patients with 189 treatment fractions were enrolled in this study. Gamma analysis was performed and the threshold that encompassed 95% of QA results (T95) was reported. The plan complexity metric was calculated for each plan and compared with the dose measurements to determine whether any correlation existed.Results. All point dose measurements were within 5% deviation. The mean gamma passing rates of the group data were found to be 96.8 ± 4.0% and 99.6 ± 0.7% with criteria of 2%/2mm and 3%/3mm, respectively. T95 of 87.4% and 98.2% was reported for the overall group with the two passing criteria, respectively. No statistically significant difference was found between adaptive treatments with adapt-to-position (ATP) and adapt-to-shape (ATS), whilst the category of pelvis data showed a better passing rate than other sites. Online QA gave a mean deviation of 0.2 ± 2.2%. The plan complexity metric was positively correlated with the mean dose difference whilst the complexity of the ATS cohort had larger variations than the ATP cohort.Conclusions. A patient-specific QA system based on ArcCHECK-MR, solid phantom and ionization chamber has been well established and implemented for validation of treatment delivery of a 1.5 T MR-Linac. Our QA data obtained over one year confirms that good agreement between TPS calculation and treatment delivery was achieved.
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Affiliation(s)
- B Yang
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - Y S Wong
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - W W Lam
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - H Geng
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - C Y Huang
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - K K Tang
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - W K Law
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - C C Ho
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - P H Nam
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - K Y Cheung
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
| | - S K Yu
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong
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Ho CC, Olding A, Fuller RO, Canty AJ, Lucas NT, Bissember AC. Suzuki–Miyaura Csp 2–Csp 2 Cross-Couplings Employing Nickel(II) Pincer Precatalysts: Mechanistic Investigations. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Curtis C. Ho
- School of Natural Sciences − Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Angus Olding
- School of Natural Sciences − Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Rebecca O. Fuller
- School of Natural Sciences − Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Allan J. Canty
- School of Natural Sciences − Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Nigel T. Lucas
- Department of Chemistry, University of Otago, Dunedin, Otago 9054, New Zealand
| | - Alex C. Bissember
- School of Natural Sciences − Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
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Jalali M, Ho CC, Fuller RO, Lucas NT, Ariafard A, Bissember AC. Photochemical Activation of a Hydroxyquinone-Derived Phenyliodonium Ylide by Visible Light: Synthetic and Mechanistic Investigations. J Org Chem 2021; 86:1758-1768. [PMID: 33377772 DOI: 10.1021/acs.joc.0c02592] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We have identified and extensively investigated the photochemical activation and reaction of a hydroxyquinone-derived phenyliodonium ylide in the presence of visible light using experiment and theory. These studies revealed that in its photoexcited state this iodonium is capable of facilitating a range of single-electron transfer (SET) processes, including hydrogen atom transfer (HAT), a Povarov-type reaction, and atom-transfer radical addition chemistry. Where possible, we have employed density functional theory (DFT) to develop a more complete understanding of these photoinduced synthetic transformations.
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Affiliation(s)
- Mona Jalali
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Curtis C Ho
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Rebecca O Fuller
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Nigel T Lucas
- Department of Chemistry, University of Otago, Dunedin, Otago 9054, New Zealand
| | - Alireza Ariafard
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Alex C Bissember
- School of Natural Sciences - Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
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Landowski LM, Livesey KL, Bibari O, Russell AM, Taylor MR, Ho CC, Howells DW, Fuller RO. Optimisation of Iron Oxide Nanoparticles for Agglomeration and Blockage in Aqueous Flow Systems. Aust J Chem 2021. [DOI: 10.1071/ch21061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Gardiner MG, Ho CC, McGuinness DS, Liu YL. Air and Moisture Tolerant Synthesis of a Chelated bis(NHC) Methylpalladium(II) Complex Relevant to Alkyl Migration Processes in Catalysis. Aust J Chem 2020. [DOI: 10.1071/ch20194] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
An air- and moisture-tolerant alternate synthetic pathway to the preparation of a cationic chelated bis(NHC) methylpalladium(ii) complex, [{(MesIm)2CH2}Pd(Me)(NCMe)][PF6], is described. The pathway involves the isolation of a bis(NHC) AgI complex, [{(MesIm)2CH2}2Ag2][PF6]2, via metallation of the corresponding diimidazolium salt with Ag2O followed by carbene transfer to [(COD)PdBrMe]. This new method avoids a previously reported unstable intermediate that displayed rapid decomposition at room temperature, attaining the targeted cationic methylpalladium(ii) complex in high yield. CO/ethylene copolymerisation catalysis trials are reported showing solvent dependent catalyst lifetime and copolymer yields. Preliminary ethylene insertion studies are also outlined revealing possible pathways leading towards catalyst deactivation.
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Wierenga TS, Vanston CR, Ariafard A, Gardiner MG, Ho CC. Accessing Chelating Extended Linker Bis(NHC) Palladium(II) Complexes: Sterically Triggered Divergent Reaction Pathways. Organometallics 2019. [DOI: 10.1021/acs.organomet.9b00356] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [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)
- Tanita S. Wierenga
- School of Natural Sciences−Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Catriona R. Vanston
- School of Natural Sciences−Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Alireza Ariafard
- School of Natural Sciences−Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Michael G. Gardiner
- School of Natural Sciences−Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Curtis C. Ho
- School of Natural Sciences−Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
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Ho CC, Ariafard A, Hyland CJT, Bissember AC. Phosphine-Scavenging Cationic Gold(I) Complexes: Alternative Applications of Gold Cocatalysis in Fundamental Palladium-Catalyzed Cross-Couplings. Organometallics 2019. [DOI: 10.1021/acs.organomet.9b00294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [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)
- Curtis C. Ho
- School of Natural Sciences − Chemistry, University of Tasmania, Hobart, Tasmania7001, Australia
| | - Alireza Ariafard
- School of Natural Sciences − Chemistry, University of Tasmania, Hobart, Tasmania7001, Australia
| | - Christopher J. T. Hyland
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Alex C. Bissember
- School of Natural Sciences − Chemistry, University of Tasmania, Hobart, Tasmania7001, Australia
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Ho CC, Deans BJ, Just J, Warr GG, Wilkinson S, Smith JA, Bissember AC. Employing Pressurized Hot Water Extraction (PHWE) to Explore Natural Products Chemistry in the Undergraduate Laboratory. J Vis Exp 2018. [PMID: 30474625 DOI: 10.3791/58195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
A recently developed pressurized hot water extraction (PHWE) method which utilizes an unmodified household espresso machine to facilitate natural products research has also found applications as an effective teaching tool. Specifically, this technique has been used to introduce second- and third-year undergraduates to aspects of natural products chemistry in the laboratory. In this report, two experiments are presented: the PHWE of eugenol and acetyleugenol from cloves and the PHWE of seselin and (+)-epoxysuberosin from the endemic Australian plant species Correa reflexa. By employing PHWE in these experiments, the crude clove extract, enriched in eugenol and acetyleugenol, was obtained in 4-9% w/w from cloves by second-year undergraduates and seselin and (+)-epoxysuberosin were isolated in yields of up to 1.1% w/w and 0.9% w/w from C. reflexa by third-year students. The former exercise was developed as a replacement for the traditional steam distillation experiment providing an introduction to extraction and separation techniques, while the latter activity featured guided-inquiry teaching methods in an effort to simulate natural products bioprospecting. This primarily derives from the rapid nature of this PHWE technique relative to traditional extraction methods that are often incompatible with the time constraints associated with undergraduate laboratory experiments. This rapid and practical PHWE method can be used to efficiently isolate various classes of organic molecules from a range of plant species. The complementary nature of this technique relative to more traditional methods has also been demonstrated previously.
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Affiliation(s)
- Curtis C Ho
- School of Natural Sciences - Chemistry, University of Tasmania
| | - Bianca J Deans
- School of Natural Sciences - Chemistry, University of Tasmania
| | - Jeremy Just
- School of Natural Sciences - Chemistry, University of Tasmania
| | | | | | - Jason A Smith
- School of Natural Sciences - Chemistry, University of Tasmania;
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Gardiner MG, Ho CC. Recent advances in bidentate bis(N-heterocyclic carbene) transition metal complexes and their applications in metal-mediated reactions. Coord Chem Rev 2018. [DOI: 10.1016/j.ccr.2018.02.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Ho CC, Olding A, Smith JA, Bissember AC. Nuances in Fundamental Suzuki–Miyaura Cross-Couplings Employing [Pd(PPh3)4]: Poor Reactivity of Aryl Iodides at Lower Temperatures. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00189] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Curtis C. Ho
- School of Natural Sciences − Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Angus Olding
- School of Natural Sciences − Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Jason A. Smith
- School of Natural Sciences − Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Alex C. Bissember
- School of Natural Sciences − Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
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Abstract
This highlight article focuses on some seminal discoveries in organopalladium(iv) chemistry and the implications and notable applications of these findings in contemporary palladium catalysis and in particular C–H activation.
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Ooi SC, Ho CC, Seow HF. Isolation of a potential anticancer agent with protein phosphatase inhibitory activity from soil-derived Penicillium sp strain H9318. TROP J PHARM RES 2016. [DOI: 10.4314/tjpr.v15i7.10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Koh RY, Lim CL, Ho CC, Uhal BD, Abdullah M, Vidyadaran S, Seow HF. Metabolites from Actinomyces strain H6552 extract inhibit transforming growth factor-mediated pulmonary fibrosis. TROP J PHARM RES 2014. [DOI: 10.4314/tjpr.v13i11.7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Ho CC, Mun KS, Naidu R. SNP array technology: an array of hope in breast cancer research. Malays J Pathol 2013; 35:33-43. [PMID: 23817393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Breast cancer is the most common malignancy in women worldwide. The incidence of breast cancer in Malaysia is lower compared to international statistics, with peak occurrence in the age group between 50 to 59 years of age and mortality rates of 18.6%. Despite current diagnostic and prognostic methods, the outcome for individual subjects remain poor. This is in part due to breast cancers' wide genetic heterogeneity. Various platforms for genetics studies are now employed to determine the identity of these genetic abnormalities, including microarray methods like high density single-nucleotide-polymorphism (SNP) oligonucleotide arrays which combine the power of chromosomal comparative genomic hybridization (cCGH) and loss of heterozygosity (LOH) in the offering of higher-resolution mappings. These platforms and their applications in highlighting the genomic alteration frameworks manifested in breast carcinoma will be discussed.
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Affiliation(s)
- C C Ho
- School of Medicine and Health Sciences, Monash University Sunway Campus, Selangor Darul Ehsan, Malaysia
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Gardiner MG, Ho CC, Mackay FM, McGuinness DS, Tucker M. Selective and adaptable access to N,N′-asymmetrically substituted imidazol-2-ylidene bis-NHC ligands: Pd(ii) complexes featuring wide variation in N-alkyl and aryl steric bulk. Dalton Trans 2013; 42:7447-57. [DOI: 10.1039/c3dt32895c] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [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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Abstract
Clinical studies show that men are more likely to develop disorders affecting midbrain dopaminergic pathways, such as drug addiction and Parkinson's disease (PD). Although a great deal of focus has been given to the role of oestrogen in the maintenance of midbrain dopaminergic pathways, little is known about how testosterone influences these pathways. In the present study, we used stereological analysis of tyrosine hydroxylase-immunoreactive (TH-IR) cell bodies to determine how testosterone influences the dopaminergic cell bodies of the substantia nigra pars compacta (SNpc) and ventral tegmental area (VTA). Rats and mice were castrated at postnatal day (PN) 60, and these midbrain cell populations were counted on PN 90. One month after castration, TH-IR cell number had increased in the SNpc and VTA of rats and mice. Replacement with testosterone or the non-aromatisable analogue dihydrotestosterone (DHT) in castrated animals reduced TH-IR cell number in the SNpc and VTA in rats. In mice, the decrease of TH-IR cell number with testosterone or DHT replacement was observed only in the SNpc. The apparent increase in TH-IR neurone number after castration is not explained by an increase in TH expression because the number of nondopaminergic cells (TH-immunonegative, TH-IN) did not decrease proportionally after castration. TH-IN cell number did not change after castration or hormone replacement in rat or mouse SNpc or VTA. These findings suggest that testosterone may play a suppressive role in midbrain dopaminergic pathways.
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Affiliation(s)
- M L Johnson
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
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Abstract
Previous findings in our laboratory and elsewhere have shown that ovariectomy of rats in adulthood attenuates cocaine-stimulated locomotor behaviour. Ovarian hormones enhance both cocaine-stimulated behaviour and increase dopamine overflow after psychomotor stimulants. The present study aimed to determine whether ovarian hormones have these effects in part by maintaining dopamine neurone number in the substantia nigra pars compacta (SNpc) and ventral tegmental area (VTA) and to investigate the roles of specific oestrogen receptors (ERs) in the maintenance of mesencephalic dopamine neurones. To accomplish this goal, we used unbiased stereological techniques to estimate the number of tyrosine hydroxylase-immunoreactive (TH-IR) cell bodies in midbrain regions of intact, ovariectomised and hormone-replaced female rats and mice. Animals received active or sham gonadectomy on postnatal day 60 and received vehicle, 17beta-oestradiol (E(2)) or selective ER agonists propyl-pyrazole-triol (PPT, ERalpha) or diarylpropionitrile (DPN, ERbeta) for 1 month post-surgery. In both rats and mice, ovariectomy reduced the number of TH-IR cells in the SNpc and VTA. Replacement with E(2), PPT or DPN prevented or attenuated the loss observed with ovariectomy in both rats and mice. An additional study using ER knockout mice revealed that adult female mice lacking ERalpha had fewer TH-IR cells in midbrain regions than wild-type mice, whereas mice lacking ERbeta had TH-IR cell counts comparable to wild-type. These findings suggest that, although both ER subtypes play a role in the maintenance of TH-IR cell number in the SNpc and VTA, ERalpha may play a more significant role.
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Affiliation(s)
- M L Johnson
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA
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Ho CC, Rohaizak M, Zulkifli SZ, Siti-Aishah MA, Nor-Aini U, Sharifah-Noor-Akmal SH. Serum sex hormone levels in pre- and postmenopausal breast cancer patients. Singapore Med J 2009; 50:513-518. [PMID: 19495523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
INTRODUCTION This study was conducted to determine the association between serum sex hormone levels and breast cancer. METHODS The study was conducted on newly-diagnosed breast cancer patients who had not received any treatment. Controls were women not known to have any breast disease or hormone-related tumours. Serum hormones were divided into quartiles. Logistic regression adjusting for age and race were done to calculate the odds ratio (OR) and 95 percent confidence interval (CI). RESULTS A total of 207 subjects were recruited; 73 premenopausal (37 cases, 36 controls) and 134 postmenopausal (68 cases and 66 controls) women. In the premenopausal women, only serum testosterone was positively associated with breast cancer (OR 1.72, 95 percent CI 0.40-7.40), but this was not a significant finding (p-value is 0.468). In the postmenopausal women, oestradiol, progesterone and testosterone were positively associated with breast cancer with a highest to lowest quartile OR of 1.48, 2.35 and 4.23 (95 percent CI 0.59-3.69, 1.11-4.95 and 1.52-11.78, respectively). The OR was significant for both progesterone and testosterone (p-values of 0.025 and 0.006, respectively). CONCLUSION There were no statistically significant findings among the premenopausal cases. In postmenopausal women, serum progesterone and testosterone levels were significantly associated positively with the odds of having breast cancer.
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Affiliation(s)
- C C Ho
- Department of Surgery, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur 56000, Malaysia.
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Ong SM, Voo LYC, Lai NS, Stark MJR, Ho CC. Screening and characterization of microbial inhibitors against eukaryotic protein phosphatases (PP1 and PP2A). J Appl Microbiol 2007; 102:680-92. [PMID: 17309617 DOI: 10.1111/j.1365-2672.2006.03135.x] [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] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIM To identify novel microbial inhibitors of protein phosphatase 1 (PP1). METHODS AND RESULTS 750 actinomycetes and 408 microfungi were isolated from Sabah forest soils and screened for production of potential PP1 inhibitors using an in vivo screening system, in which candidate inhibitors were identified through mimicking the properties of PP1-deficient yeast cells. Acetone extracts of two fungi, H9318 (Penicillium) and H9978 (non-Penicillium) identified in this way showed inhibitory activity towards both mammalian PP1 and PP2A in an in vitro phosphatase assay, while extract from H7520 (Streptomyces) inhibited PP2A but not PP1. Consistently, using a drug-induced haploinsufficiency test, strains with either reduced PP1 or PP2A function were hypersensitive to H9318 and H9978 extracts whereas only the latter strain showed hypersensitivity to H7250 extract. H9318 extract was fractionated using RP-HPLC into two active peaks (S1 and S2). A yeast strain with reduced PP1 function showed hypersensitivity to fraction S2 whereas a strain with reduced PP2A function was hypersensitive to fraction S1. However, S1 and S2 inhibited both PP1 and PP2A activities to a similar extent. CONCLUSION Three candidate PP inhibitors have been identified. SIGNIFICANCE AND IMPACT OF THE STUDY Further development may generate useful research tools and ultimately therapeutic agents.
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Affiliation(s)
- S M Ong
- Biotechnology Program, School of Science and Technology, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia
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Abstract
The aim was to evaluate the practice of hiding the needle prior to dental anesthesia administration to children. Fourteen 5 and 6 year olds received dental treatment in two sessions. The needle was shown in one session and hidden in the other. Eleven children were cooperative and 3 uncooperative irrespective of approach. The children's behavior correlated with fears expressed by the mothers. Our initial fndintgs do not support the practice of hiding the needle.
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Affiliation(s)
- G M Maragakis
- Department of Pediatric Dentistry, Louisiana State University School of Dentistry, USA.
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Chang SJ, Niu GCC, Kuo SM, Ho CC, Bair MS. Preparation of nano-sized particles from collagen II by a high-voltage electrostatic field system. ACTA ACUST UNITED AC 2006; 153:1-6. [PMID: 16480319 DOI: 10.1049/ip-nbt:20050037] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The pilot study describes a novel method for preparing nano-sized particles from collagen II using a high-voltage electrostatic field system. Observations from transmission electron microscopy showed that, in one of the cases, the nano-sized collagen II particles exhibited good sphericity, and the particles were in the range of 23.3+/-1.7 nm in diameter at the experimental setting of 3 kV cm(-1), for a 3 h treatment period and at 25 degrees C (with a collagen concentration of 0.2 mg ml(-1)). When the treatment temperature increased to 30 degrees C, the collagen II began to lose the tendency to form individually separated spherically shaped nano-particles. Moreover, a fibrous structure of collagen II was formed instead of a nano-particle shape at the temperature of 37 degrees C. This result is probably contributed to by an entropy-driven process that is termed fibrillogenesis, a larger force causing the collagen molecules to self-assemble and then form collagen fibrils. It is interesting to note that this is practically the first attempt to produce nano-particles directly from collagen II solution under the treatment of a high-voltage electrostatic field, together with a set of working parameters for the collagen concentration and low-temperature setting.
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Affiliation(s)
- S J Chang
- I-SHOU University, Department of Biomedical Engineering, Kaohsiung County, Taiwan
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Huang CR, Lin SS, Chou MY, Ho CC, Wang L, Lee YL, Chen CS, Yang CC. Demonstration of different modes of cell death upon herpes simplex virus 1 infection in different types of oral cells. Acta Virol 2005; 49:7-15. [PMID: 15929393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The effects of Herpes simplex virus 1 (HSV-1) infection on five different types of oral cancerous cells (neck metastasis of gingival carcinoma (GNM) cells and tongue squamous cells of carcinoma (TSCCa) and non-cancerous cells (buccal mucosal fibroblasts (BF), gingival fibroblasts (GF), oral submucosal fibrosis cells (OSF)) and one type of non-oral cancerous cells (KB cells) were investigated. In HSV-1-infected cells the cell viability, CPE, viral antigens accumulation, caspase-3 activity, annexin V binding and DNA fragmentation were estimated. Three different forms or pathways of cell death were considered: apoptosis (the presence or rise of caspase-3 activity, DNA fragmentation and annexin V binding), slow cell death (the presence or rise of DNA fragmentation, the absence or decline of caspase-3 activity and annexin V binding), and necrosis (the absence of decline of caspase-3 activity, DNA fragmentation and annexin V binding). The viability of all cell types, except for KB cells, was reduced by the infection. CPE and viral antigens data demonstrated that all six types of cells could be infected with HSV-1. Upon HSV-1 infection there occurred (i) a classical apoptosis in GF cells, (ii) apoptosis in the early phase of infection and necrosis in the late phase of infection in GNM and TSCCa cells, (iii) slow cell death followed by necrosis in BF and OSF cells (however, these cells showed a different type of CPE), (iv) a classical slow cell death in KB cells. It is hypothesized that HSV-1 infection has a potential to induce several distinct pathways leading to cell death or several forms of cell death. Moreover, more than one pathway may be involved in the death of particular cell type. As HSV-1 was demonstrated to infect different oral and non-oral cells and cause different pathways or forms of cell death, the safety of using HSV-1 as a vector for gene therapy should be re-considered.
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Affiliation(s)
- C R Huang
- Institute of Immunology, Chung Shan Medical University Hospital, Taichung, Taiwan, Republic of China
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Chen YS, Ho CC, Cheng KC, Tyan YS, Hung CF, Tan TW, Chung JG. Curcumin inhibited the arylamines N-acetyltransferase activity, gene expression and DNA adduct formation in human lung cancer cells (A549). Toxicol In Vitro 2003; 17:323-33. [PMID: 12781211 DOI: 10.1016/s0887-2333(03)00020-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [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: 01/29/2023]
Abstract
It is well known that N-acetyltransferase (NAT) plays an important role in the arylamine metabolism. We analysed the response of A549 human lung cancer cells for N-acetylation of 2-aminofluorene (AF) to curcumin. After curcumin treatment, the NAT activity was examined by HPLC, AF-DNA adduct formation was examined by HPLC, and NAT gene expression by polymerase chain reaction were detected. The NAT activity in the human A549 cells and cytosols was suppressed by curcumin in a dose-dependent manner. The results also demonstrated that gene expression (NAT1 mRNA) in human lung A549 tumor cells was inhibited and decreased by curcumin. After the incubation of human lung A549 tumor cells with AF with or without curcumin co-treatment, the cells were recovered and DNA was prepared and hydrolyzed to nucleotides. The adducted nucleotides were extracted into butanol and analyzation of AF-DNA adducts was done by HPLC. The results also demonstrated that curcumin decreases AF-DNA adduct formation in the human lung A549 tumor cells.
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Affiliation(s)
- Y S Chen
- Department of Nutrition, China Medical College, 91 Hsueh-Shih Road, 404, ROC, Taichung, Taiwan
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Pei RJ, Liu YH, Su B, Yeh CC, Lee KY, Yeh KT, Hsu YH, Ho CC, Lai YS. Do the CK18 related proteins change in general in epithelial cancers? Res Commun Mol Pathol Pharmacol 2002; 108:253-60. [PMID: 11913716] [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: 02/24/2023]
Abstract
The modulation of cytokeratin 18 during tumor transformation in hepatoma had been previously recognized through a series of biochemical and immunological approaches. Expression of cytokeratin 18 in transitional cell carcinoma comparing with hepatoma was investigated using the hepatoma transformation model. CK18 related molecules were found. In the present study, we design various epithelial cancers with the same model. CK18 related molecules were all evident. Therefore, we suggest that CK18 related proteins would play an important role in tumorigenesis of epithelial cancers.
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Affiliation(s)
- R J Pei
- Department of Pathology, School of Medicine, China Medical College, Taichung, Taiwan
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Huang HY, Ho CC, Huang PH, Hsu SM. Co-expression of VEGF-C and its receptors, VEGFR-2 and VEGFR-3, in endothelial cells of lymphangioma. Implication in autocrine or paracrine regulation of lymphangioma. J Transl Med 2001; 81:1729-34. [PMID: 11742043 DOI: 10.1038/labinvest.3780386] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Lymphangioma has long been thought of as congenital malformations resulting from the failure of lymphatic vessels communicating with the venous system in the fetal period. Alternatively, it is proposed to be true neoplasm originated from the transformation of lymphatic endothelia. To extend the molecular basis of the pathogenesis of lymphangioma, we have characterized the expression of vascular endothelial growth factor (VEGF) and VEGF receptors (VEGFR) in 29 cases of lymphangioma by RNA in situ hybridization. Endothelial cells of lymphangioma co-express transcripts of VEGF-C and its receptors VEGFR-3 (Flt4) and VEGFR-2 (Flk1), which are not detectable in the adjacent connective tissue. In contrast, there is little or no expression of VEGF-C, VEGFR-3, and VEGFR-2 mRNA in endothelial cells of hemangiomas, angiosarcomas, or normal lymphatic vessels of the small or large intestines. The results suggest that VEGF-C and its receptors may take active parts in the formation of lymphangioma by autocrine or paracrine regulation.
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Affiliation(s)
- H Y Huang
- Department of Pathology, National Taiwan University College of Medicine and National Taiwan University Hospital, Taipei, Taiwan
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Bajwa ZH, Ho CC. Herpetic neuralgia. Use of combination therapy for pain relief in acute and chronic herpes zoster. Geriatrics (Basel) 2001; 56:18-24. [PMID: 11766559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
Herpes zoster (shingles) is a localized infection that begins in the dorsal root ganglla of the cranial or spinal nerves and spreads as a rash over the corresponding dermatome. It usually is caused by reactivation of latent varicella-zoster virus remaining from childhood chicken pox. Postherpetic neuralgia (PHN) is a chronic neuropathic pain syndrome that occurs as a complication of shingles, most commonly in older persons. Acute zoster and PHN can be severe conditions associated with impaired sleep, decreased appetite, depression, anxiety disorder, and diminished libido. Management of zoster-related pain should begin as soon as possible after the onset of symptoms. Combination therapy--including antiviral, antidepressant, corticosteroid, opioid, and topical agents--provides the most effective analgesia.
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Ho CC, Tsai HY, Lai YS, Chung JG. Ellagic acid inhibited 2-aminofluorene and p-aminobenzoic acid acetylation by mononuclear leucocytes from Sprague-Dawley rats. Cytobios 2001; 104:107-17. [PMID: 11258539] [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: 02/19/2023]
Abstract
Following exposure of rats to the arylamine carcinogen 2-aminofluorene, DNA-carcinogen adducts were found in the liver and bladder target tissues, and also in circulating leucocytes. This work investigated the effect of ellagic acid on arylamine (2-aminofluorene and p-aminobenzoic acid) acetylations in rat leucocytes. Evidence is presented that rat mononuclear leucocytes are capable of acetylating 2-aminofluorene and p-aminobenzoic acid. Both lymphocytes and monocytes were able to acetylate arylamines during 18 h of culture. Cultured lymphocytes produced about twice as much N-acetyl-2-aminofluorene from 2-aminofluorene and 2.2-fold as much N-acetyl-p-aminobenzoic acid from p-aminobenzoic acid as monocytes. After cotreatment with ellagic acid the lymphocyte and monocyte cultures indicated that ellagic acid reduced 2-aminofluorene acetylation.
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Affiliation(s)
- C C Ho
- Department of Physiology, China Medical College, Taichung, Taiwan, Republic of China
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Cheo SH, Wang P, Tan KL, Ho CC, Kang ET. Surface modification of natural rubber latex films via grafting of poly(ethylene glycol) for reduction in protein adsorption and platelet adhesion. J Mater Sci Mater Med 2001; 12:377-384. [PMID: 15348275 DOI: 10.1023/a:1011280416520] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Natural rubber (NR) latex films with surface grafted poly(ethylene glycol) (PEG) chains were prepared by UV-induced graft copolymerization of methoxy poly(ethylene glycol) monomethacrylate (PEGMA) onto the plasma-pretreated NR latex films. PEGMA macromononers of different molecular weights were used. The UV-induced graft copolymerization of PEGMA onto the plasma-pretreated NR latex films was also explored with PEGMA of different macromonomer concentrations and with different UV graft copolymerization time. The surface microstructures and compositions of the PEG-modified NR latex films were characterized by contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) measurements. In general, higher macromonomer concentration and longer UV graft copolymerization time led to a higher graft yield. Water contact angle measurements revealed that the hydrophilicity of the NR latex film surface was greatly enhanced by the grafting of the PEG chains. The NR surface with a high density of grafted PEG was very effective in reducing protein adsorption and platelet adhesion. A lower graft concentration of the high-molecular-weight PEG was more effective than a high graft concentration of the low-molecular-weight PEG in reducing protein adsorption and platelet adhesion.
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Affiliation(s)
- S H Cheo
- Swarthmore College, 500 College Avenue, Swarthmore, PA 19081, USA
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Chung JG, Chen GW, Hung CF, Lee JH, Ho CC, Ho HC, Chang HL, Lin WC, Lin JG. Effects of berberine on arylamine N-acetyltransferase activity and 2-aminofluorene-DNA adduct formation in human leukemia cells. Am J Chin Med 2001; 28:227-38. [PMID: 10999441 DOI: 10.1142/s0192415x00000271] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Berberine is an alkaloid occurring in the plant genera Berberis and Coptis. Although berberine had been demonstrated to have antineoplastic function by inhibiting DNA-synthesis in activated lymphocytes, there is no available information to address berberine affects on human leukemia cell N-acetyltransferase (NAT) activity and 2-aminofluorene (AF)-DNA adduct formation. Thus, berberine was tested for inhibition of arylamine NAT activity and AF-DNA adduct formation in human leukemia cells. The NAT activity was measured by a high performance liquid chromatography assaying for the amounts of N-acetyl-2-aminofluorene (AAF) and N-acetyl-p-aminobenzoic acid (N-Ac-PABA) and the remaining AF and p-aminobenzoic acid (PABA). The NAT activity and AF-DNA adduct formation in human leukemia cells were inhibited by berberine in a dose-dependent manner, i.e. the higher the concentration of berberine, the higher the inhibition of NAT activity and AF-DNA adduct. The data also indicate that berberine decreased the apparent values of Km and Vmax from human leukemia cells in both cytosol and intact cells.
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Affiliation(s)
- J G Chung
- Department of Microbiology, China Medical College, Taichung, Taiwan
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Abstract
In the present study, we examined whether fear of pain, dental fear, general indices of psychological distress, and self-reported stress levels differed between 40 orofacial pain patients and 40 gender and age matched control general dental patients. We also explored how fear of pain, as measured by the Fear of Pain Questionnaire-III (J Behav Med 21 (1998) 389), relates to established measures of psychological problems in our sample of patients. Finally, we examined whether fear of pain uniquely and significantly predicts dental fear and psychological distress relative to other theoretically-relevant psychological factors. Our results indicate that fear of severe pain and anxiety-related distress, broadly defined, are particularly elevated in orofacial pain patients relative to matched controls. Additionally, fear of pain shares a significant relation with dental fear but not other general psychological symptomology, and uniquely and significantly predicts dental fear relative to other theoretically-relevant variables. Taken together, these data, in conjunction with other recent studies, suggest greater attention be placed on understanding the fear of pain in orofacial pain patients and its relation to dental fear and anxiety.
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Affiliation(s)
- D W McNeil
- Anxiety, Psychophysiology and Pain Research Laboratory, Department of Psychology, West Virginia University, Morgantown, WV 26506-6040, USA.
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Tsai SJ, Ting H, Ho CC, Bih LI. Use of sonography and radioisotope renography to diagnose hydronephrosis in patients with spinal cord injury. Arch Phys Med Rehabil 2001; 82:103-6. [PMID: 11239294 DOI: 10.1053/apmr.2001.16344] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [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: 11/11/2022]
Abstract
OBJECTIVE To study the accuracy of sonography and radioisotope renography in detecting hydronephrosis in patients with spinal cord injury (SCI). DESIGN Prospective, blinded comparison study. SETTING Rehabilitation hospital affiliated with a medical college. PARTICIPANTS One hundred and nine patients with SCI (21 women, 88 men) participated. INTERVENTIONS Comprehensive urologic examinations including clinical evaluation, laboratory tests, intravenous urography (IVU), sonography, radioisotope renography (renal scan), voiding cystourethrography, and cystometry. The findings at sonography and renal scan were separately compared with the final diagnosis interpreted by IVU and clinical findings. MAIN OUTCOME MEASURES Effective renal plasma flow, pyelocaliectasis, and positive and negative predictive value. RESULTS A total of 235 kidneys were analyzed. Sonography correctly excluded the presence of hydronephrosis in 173 of 192 nonobstructed kidneys. Sonograms were interpreted as positive in 41 of 43 kidneys with documented hydronephrosis. Renal scan correctly excluded 161 nonobstructed kidneys. The renal scan detected 39 of 43 kidneys with hydronephrosis. The sensitivity of sonography was.96 with a specificity of.90. Renal scan reached a sensitivity of.91 with a specificity of.84. CONCLUSION Sonography and renal scan are safe, sensitive, and specific for detecting hydronephrosis. Combined use of both methods appears to be a reliable alternative to IVU in the long-term follow-up for patients with SCI with neurogenic bladder dysfunction.
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Affiliation(s)
- S J Tsai
- Department of Rehabilitation Medicine, Chung Shan Medical and Dental College, Taiwan
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Abstract
Previous studies of protein fouling during microfiltration have shown significant discrepancies between filtrate flux data and predictions of the classical pore blockage, pore constriction, and cake filtration models. A new mathematical model was developed for the filtrate flux which accounts for initial fouling due to pore blockage and subsequent fouling due to the growth of a protein cake or deposit over these initially blocked regions. The model explicitly accounts for the inhomogeneity in the cake layer thickness over different regions of the membrane arising from the time-dependent blockage of the pore surface. The model was shown to be in excellent agreement with experimental data obtained during the stirred cell filtration of bovine serum albumin solutions through polycarbonate track-etched microfiltration membranes over the entire course of the filtration. The model provides a smooth transition from the pore blockage to cake filtration regimes, eliminating the need to use different mathematical formulations to describe these two phenomena. In addition, the model provides the first quantitative explanation for some of the unusual observations reported previously in investigations of protein microfiltration. The results provide important insights into the underlying mechanisms of protein fouling during microfiltration. Copyright 2000 Academic Press.
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Affiliation(s)
- CC Ho
- Department of Chemical Engineering, University of Delaware, Newark, 19716, Delaware
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Lin SS, Hung CF, Ho CC, Liu YH, Ho HC, Chung JG. Effects of ellagic acid by oral administration on N-acetylation and metabolism of 2-aminofluorene in rat brain tissues. Neurochem Res 2000; 25:1503-8. [PMID: 11071370 DOI: 10.1023/a:1007632326953] [Citation(s) in RCA: 9] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Numerous studies have demonstrated that the Acetyl Coenzyme A-dependent arylamine NAT enzyme exist in many tissues of experimental animals including humans, and that NAT has been shown to be exist in mouse brain tissue. Increased NAT activity levels are associated with increased sensitivity to the mutagenic effects of arylamine carcinogens. Attenuation of liver NAT activity is related to breast and bladder cancer processes. Therefore, the effects of ellagic acid (EA) on the in vitro and in vivo N-acetylation of 2-aminofluorene (AF) were investigated in cerebrum, cerebellum and pineal gland tissues from male Sprague-Dawley rats. For in vitro examination, cytosols with or without EA (0.5-500 microM) co-treatment decreased 7-72%, 15-63% and 10-78% of AF acetylation for cerebrum, cerebellum and pineal gland tissues, respectively. For in vivo examination, EA and AF at the same time treated groups with all 3 examined tissues did show significant differences (the changes of total amounts of AF and AF metabolites based on the Anova analysis) when compared to the ones without EA cotreatment rats. The pretreatment of male rats with EA (10 mg/kg) 24 hr prior to the administration of AF (50 mg/kg) (one day of EA administration suffice to induce large changes in phase II enzyme activity) resulted in a 76% decrease in total AF and metabolites in pineal gland but did not show significant differences in cerebrum and cerebellum tissues. This is the first demonstration to show that EA decreases the N-acetylation of carcinogens in rat brain tissues.
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Affiliation(s)
- S S Lin
- Department of Radiological Technology, Chungtai Institute of Health Sciences and Technology, Taichung, Taiwan, Republic of China
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Yeh CC, Pei RJ, Liu YH, Su B, Lee KY, Yeh KT, Hsu YH, Ho CC, Ho HC, Lai YS. The expression of cytokeratin 18 in transitional cell carcinoma comparing with hepatoma. Res Commun Mol Pathol Pharmacol 2000; 105:3-10. [PMID: 10850364] [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: 02/16/2023]
Abstract
The epithelium in kidneys and urinary bladders contain CK18 as in liver cells. The modulation of cytokeratin 18 during tumor transformation in hepatoma had been previously recognized through a series of biochemical and immunological approaches. A 14 KD hepatoma related molecules was found in the previous studies. We would like to utilize the hepatoma transformation model to study the changes in CK18 in transitional cell carcinoma, using immunoblotting and western blotting techniques. The result is that transitional cell carcinoma retain their CK18 molecule. Furthermore, CK18 related molecules similar to those seen in hepatoma also present in transitional cell carcinoma. The conclusions are transitional cell carcinoma contains CK18 related proteins similar to those seen in hepatoma tissues. We suggest that this element would be responsible for the change during the malignant transformation processes.
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Affiliation(s)
- C C Yeh
- Department of Urology, School of Medicine The China Medical College and Hospital Taichung, Taichung City, Taiwan, ROC
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