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Articles 391 - 416 of 416
Full-Text Articles in Physical Sciences and Mathematics
Asymmetric Synthesis Of Polyfunctionalized Pyrrolidines And Related Alkaloids, Stephen G. Pyne, Andrew S. Davis, Nicole Gates, Joseph Hartley, Karl Lindsay, Theeraphan Machan, Minyan Tang
Asymmetric Synthesis Of Polyfunctionalized Pyrrolidines And Related Alkaloids, Stephen G. Pyne, Andrew S. Davis, Nicole Gates, Joseph Hartley, Karl Lindsay, Theeraphan Machan, Minyan Tang
Faculty of Science - Papers (Archive)
This account describes our recent studies on the development of a general method of preparing polyfunctionalized pyrrolidine, indolizidine, pyrrolizidine and pyrrolo[1,2-a]azepines and their related alkaloids.
Plasminogen Binding By Group A Streptococcal Isolates From A Tropical Region With Hyperendemic Streptococcal Skin Infection And A High Incidence Of Invasive Infection, F. C. Mckay, Jason D. Mcarthur, Martina L. Sanderson-Smith, S. Gardam, B. J. Currie, K. S. Sriprakash, P. K. Fagan, R. J. Towers, M. R. Batzloff, G. S. Chhatwal, Marie Ranson, Mark J. Walker
Plasminogen Binding By Group A Streptococcal Isolates From A Tropical Region With Hyperendemic Streptococcal Skin Infection And A High Incidence Of Invasive Infection, F. C. Mckay, Jason D. Mcarthur, Martina L. Sanderson-Smith, S. Gardam, B. J. Currie, K. S. Sriprakash, P. K. Fagan, R. J. Towers, M. R. Batzloff, G. S. Chhatwal, Marie Ranson, Mark J. Walker
Faculty of Science - Papers (Archive)
Reports of resurgence in invasive group A streptococcal (GAS) infections come mainly from affluent populations with infrequent exposure to GAS. In the tropical Northern Territory (NT) of Australia, high incidence of invasive GAS disease is secondary to endemic skin infection; serotype M1 clones are rare in invasive infection; the diversity and level of exposure to GAS strains is high and no particular strains dominate. Expression of a plasminogen-binding group A streptococcal M-like protein (PAM) has been associated with skin infection in isolates elsewhere (Bessen, D., C.M. Sotir, T.M. Readdy, and S.K. Hollingshead.1996. J. Infect. Dis. 173:896-900) and subversion of the …
Poly(2-Alkylacrylic Acid) Polymers Deliver Molecules To The Cytosol By Ph-Sensitive Disruption Of Endosomal Vesicles, Rachel A. Jones, C. Y. Cheung, F. E. Black, J. K. Zia, P. S. Stayton, A. S. Hoffman, Mark R. Wilson
Poly(2-Alkylacrylic Acid) Polymers Deliver Molecules To The Cytosol By Ph-Sensitive Disruption Of Endosomal Vesicles, Rachel A. Jones, C. Y. Cheung, F. E. Black, J. K. Zia, P. S. Stayton, A. S. Hoffman, Mark R. Wilson
Faculty of Science - Papers (Archive)
The permeability barrier posed by cell membranes represents a challenge for the delivery of hydrophilic molecules into cells. We previously proposed that poly(2- alkylacrylic acid)s are endocytosed by cells into acidified vesicles and are there triggered by low pH to disrupt membranes and release the contents of endosomes/lysosomes to the cytosol. If this hypothesis is correct, these polymers could be valuable in drug delivery applications. This report provides functional comparisons of a family of three poly(2-alkylacrylic acid)s. Poly(2-propylacrylic acid) (PPAA), poly(2-ethylacrylic acid) (PEAA), and poly(2-methylacrylic acid) (PMAA) were compared in red blood cell haemolysis assays and in a lipoplex gene …
Novel Pharmacophore Based Methods Reveal Gossypol As A Reverse Transcriptase Inhibitor, Paul A. Keller, C. Birch, S. P. Leach, D. Tyssen, R. Griffith
Novel Pharmacophore Based Methods Reveal Gossypol As A Reverse Transcriptase Inhibitor, Paul A. Keller, C. Birch, S. P. Leach, D. Tyssen, R. Griffith
Faculty of Science - Papers (Archive)
In a program to identify new structural entities for the inhibition of the HIV-1 reverse transcriptase (RT) enzyme via database searching, a series of RT pharmacophores were developed. By utilising a novel filtering technique, the National Cancer Institute database of compounds was scanned producing 15 compounds to be screened for activity. A notable inclusion was a series of gossypol derivatives. The testing of a series of compounds revealed the parent compound gossypol to be an HIV-1 reverse transcriptase inhibitor. These results suggest that at least part of its anti-HIV activity is due to gossypol targeting the non-nucleoside inhibitor binding pocket …
Probing Dna Selectivity Of Ruthenium Metallointercalators Using Esi Mass Spectrometry, Jennifer L. Beck, Rajesh Gupta, Thitima Urathamakul, Nyree L. Williamson, Margaret Sheil, Janice Aldrich-Wright, Stephen F. Ralph
Probing Dna Selectivity Of Ruthenium Metallointercalators Using Esi Mass Spectrometry, Jennifer L. Beck, Rajesh Gupta, Thitima Urathamakul, Nyree L. Williamson, Margaret Sheil, Janice Aldrich-Wright, Stephen F. Ralph
Faculty of Science - Papers (Archive)
ESI mass spectra show that up to five ruthenium molecules can bind non-covalently to double stranded 16mer DNA, and provide information on the relative affinity and DNA sequence selectivity of different ruthenium complexes.
Asymmetric Synthesis Of (-)-7-Epiaustraline And (+)-1,7-Diepiaustraline, Minyan Tang, Stephen G. Pyne
Asymmetric Synthesis Of (-)-7-Epiaustraline And (+)-1,7-Diepiaustraline, Minyan Tang, Stephen G. Pyne
Faculty of Science - Papers (Archive)
A diastereoselective and modular approach to the synthesis of the 3-hydroxymethyl-2,3,5,6,7,7a-hexahydro-1H-pyrrolizine-1,2,7-triol structure, characteristic of several natural pyrrolizidine natural products has been developed. This approach culminated in the synthesis of (-)-7-epiaustraline and (+)-1,7-diepiaustraline. The oxazolidinone group has been found to be a useful protecting group in the RCM reaction and, as part of a pyrrolo[1,2-c]oxazol-3-one ring system, has functioned as a stereo- and regio-directing group, in a key diastereoselective cis-dihydroxylation reaction and a regioselective nucleophilic ring-opening of a S,S-dioxo-dioxathiole.
Chemo-Enzymatic Synthesis Of (-)-Epipentenomycin I, Tawesin Klomklao, Stephen G. Pyne, Apiwat Baramee, Brian W. Skelton, Allan H. White
Chemo-Enzymatic Synthesis Of (-)-Epipentenomycin I, Tawesin Klomklao, Stephen G. Pyne, Apiwat Baramee, Brian W. Skelton, Allan H. White
Faculty of Science - Papers (Archive)
A chemo-enzymatic synthesis of (−)-epipentenomycin I is reported using a lipase-catalysed kinetic resolution of the racemic pentacyclic alcohol 8. Flash vacuum pyroloysis of (−)-8 so obtained gave (−)-(4R)-4-hydroxy-5-methylene-2-cyclopentenone. Epoxidation of this compound with dimethyldioxirane followed by hydrolytic ring-opening of the resulting epoxide gave (−)-epipentenomycin I.
The Prevention Of Preterm Labour – Corticotropin Releasing Hormone Type 1 Receptors As A Target For Drug Design And Development, Paul A. Keller, K. Kirkwood, J. Morgan, S. Westcott, A. Mccluskey
The Prevention Of Preterm Labour – Corticotropin Releasing Hormone Type 1 Receptors As A Target For Drug Design And Development, Paul A. Keller, K. Kirkwood, J. Morgan, S. Westcott, A. Mccluskey
Faculty of Science - Papers (Archive)
The role of the corticotropin releasing hormone in the onset of labour and the subsequent medicinal chemistry implications of CRH antagonists for the prevention of premature birth, and identification of the CRH type 1 receptor as the target for this drug design, are reviewed here.
Development Of A Simple, Self-Consistent Polarizable Model For Liquid Water, Haibo Yu, Tomas Hansson, Wilfred Van Gunsteren
Development Of A Simple, Self-Consistent Polarizable Model For Liquid Water, Haibo Yu, Tomas Hansson, Wilfred Van Gunsteren
Faculty of Science - Papers (Archive)
The charge-on-spring method is used to develop a rigid, three-site, polarizable water model, a noniterative and a self-consistent version. In this method, the polarizability is taken into account by a variable separation of charges on selected polarizable centers. One of the pair of polarization charges resides on a polarizable center, while the other one is treated as an additional particle attached to the polarizable center by a parabolic restraint potential. The separation is calculated in response to the instantaneous electric field. We parametrized two models which are based on noniterative and self-consistent versions of the method, respectively. We computed several …
Tyrosine Phosphorylation Of Hsp-90 During Mammalian Sperm Capacitation, Heath W. Ecroyd, Russell C. Jones, Robert J. Aitken
Tyrosine Phosphorylation Of Hsp-90 During Mammalian Sperm Capacitation, Heath W. Ecroyd, Russell C. Jones, Robert J. Aitken
Faculty of Science - Papers (Archive)
The process of sperm capacitation is correlated with activation of a signal transduction pathway leading to protein tyrosine phosphorylation. Whereas phosphotyrosine expression is an essential prerequisite for fertilization, the proteins that are phosphorylated during capacitation have not yet been identified. In the present study, we observed that a major target of this signaling pathway is the molecular chaperone protein, heat shock protein (HSP)-86, a member of the HSP-90 family of HSPs. We used cross-immunoprecipitation experiments to confirm the tyrosine phosphorylation of HSP-86, a process that is not inhibited by the ansamycin antibiotic, geldanamycin. The general significance of these findings was …
Endogenous Redox Activity In Mouse Spermatozoa And Its Role In Regulating The Tyrosine Phosphorylation Events Associated With Sperm Capacitation, Heath W. Ecroyd, Russell C. Jones, Robert J. Aitken
Endogenous Redox Activity In Mouse Spermatozoa And Its Role In Regulating The Tyrosine Phosphorylation Events Associated With Sperm Capacitation, Heath W. Ecroyd, Russell C. Jones, Robert J. Aitken
Faculty of Science - Papers (Archive)
We investigated the role of endogenous redox activity in regulating the signal transduction pathway leading to tyrosine phosphorylation in mouse spermatozoa. Endogenous redox activity was monitored using a luminol-peroxidase chemiluminescent probe. Chemiluminescence increased in spermatozoa that were actively undergoing cAMP-mediated tyrosine phosphorylation events associated with capacitation and was inhibited in a dose-dependent manner by addition of catalase or diphenylene iodonium, both of which also inhibited tyrosine phosphorylation within the cell at points downstream of cAMP. Excluding bicarbonate from the incubation medium reduced the redox activity of sperm by 80-90% and dramatically reduced tyrosine phosphorylation. This study provides the first evidence …
Stemocurtisine, The First Pyrido[1,2-A]Azapine Stemona Alkaloid, Pitchaya Mungkornasawakul, Stephen G. Pyne, Araya Jatisatienr, Damrat Supyen, Wilford Lie, Alison T. Ung, Brian W. Skelton, Allan H. White
Stemocurtisine, The First Pyrido[1,2-A]Azapine Stemona Alkaloid, Pitchaya Mungkornasawakul, Stephen G. Pyne, Araya Jatisatienr, Damrat Supyen, Wilford Lie, Alison T. Ung, Brian W. Skelton, Allan H. White
Faculty of Science - Papers (Archive)
A new pentacyclic stemona alkaloid, stemocurtisine (2), with a novel pyrido[1,2-a]azapine A,B-ring system, has been isolated from a root extract of Stemona curtisii. The structure and relative stereochemistry was determined by spectral data interpretation and X-ray crystallography.
Evolution Of Chemical Contaminant And Toxicology Studies, Part 1 - An Overview, Dianne F. Jolley, Glennys A. O'Brien, Robert John Morrison
Evolution Of Chemical Contaminant And Toxicology Studies, Part 1 - An Overview, Dianne F. Jolley, Glennys A. O'Brien, Robert John Morrison
Faculty of Science - Papers (Archive)
The study of environmental chemical contaminants and their toxicological effects has changed dramatically over the last 50 years. Initially studies concentrated on trying to identify what contaminants were actually present and to develop quantitative methods to determine the concentrations (total) present. Health impacts were often investigated independently in medical research centres. With improving analytical techniques, studies of the speciation of contaminants began and the specific forms that were creating the major problems were gradually identified. Continuing improvements in analytical chemistry, together with a move towards more integrated and multidisciplinary research now sees chemists, biologists, toxicologists and health researchers working closely …
Evolution Of Chemical Contaminant And Toxicology Studies, Part 2- Case Studies Of Selenium And Arsenic, Glennys O'Brien, Dianne Jolley, Robert John Morrison
Evolution Of Chemical Contaminant And Toxicology Studies, Part 2- Case Studies Of Selenium And Arsenic, Glennys O'Brien, Dianne Jolley, Robert John Morrison
Faculty of Science - Papers (Archive)
As the second of a two part series discussing the evolution of the field of environmental toxicology, this paper presents two case studies: selenium and arsenic. Developments over several decades in the understanding of the behaviour of arsenic and selenium in different chemical forms in various compartments of the environment are discussed. Selenium was initially thought to be toxic, but later investigations showed it to be an essential micronutrient with a variety of biochemical functions, and, importantly, that there is a very narrow gap between the essential and the toxic body burden. Arsenic, on the other hand, has not yet …
Streptococcus Pyogenes Prtfii, But Not Sfbi, Sfbii Or Fbp54, Is Represented More Frequently Among Invasive-Disease Isolates Of Tropical Australia, A. Delvecchio, B. J. Currie, Jason D. Mcarthur, Mark J. Walker, K. S. Sriprakash
Streptococcus Pyogenes Prtfii, But Not Sfbi, Sfbii Or Fbp54, Is Represented More Frequently Among Invasive-Disease Isolates Of Tropical Australia, A. Delvecchio, B. J. Currie, Jason D. Mcarthur, Mark J. Walker, K. S. Sriprakash
Faculty of Science - Papers (Archive)
Streptococcus pyogenes (group A streptococcus) strains may express several distinct ®bronectinbinding proteins (FBPs) which are considered as major streptococcal adhesins. Of the FBPs, SfbI was shown in Šitro to promote internalization of the bacterium into host cells and has been implicated in persistence. In the tropical Northern Territory, where group A streptococcal infection is common, multiple genotypes of the organism were found among isolates from invasive disease cases and no dominant strains were observed. To determine whether any FBPs is associated with invasive disease propensity of S. pyogenes, we have screened streptococcal isolates from bacteraemic and necrotizing fasciitis patients and …
Synthesis Of Chiral Allylic Amines Via Palladium(0) Catalysed Allylations Of Allylic Carbonates With Chiral Sulfinamide Anions, Zemin Dong, Stephen G. Pyne
Synthesis Of Chiral Allylic Amines Via Palladium(0) Catalysed Allylations Of Allylic Carbonates With Chiral Sulfinamide Anions, Zemin Dong, Stephen G. Pyne
Faculty of Science - Papers (Archive)
The palladium(0) catalysed allylation reactions of allylic carbonates with chiral sulfinamide anions to give unstable allylic sulfinamide products are described. These products are readily converted to stable, chiral N-benzoyl or N-tosyl allylic amine derivatives with poor to modest enantiomeric purities (ee 23-41%).
Considerations For Capping Metal-Contaminated Sediments In Dynamic Estuarine Environments, Stuart L. Simpson, Ian D. Pryor, Ben R. Mewburn, Graeme E. Batley, Dianne F. Jolley
Considerations For Capping Metal-Contaminated Sediments In Dynamic Estuarine Environments, Stuart L. Simpson, Ian D. Pryor, Ben R. Mewburn, Graeme E. Batley, Dianne F. Jolley
Faculty of Science - Papers (Archive)
The effects of tides, bioturbating organisms and periods of anoxia on metal fluxes from contaminated harbour sediments in a shallow tidal estuarine bay were studied, together with capping technology options for the containment of metal contaminants. Zinc fluxes from the sediments were high, ranging from 10 to 89 mg Zn /m2/day. In the absence of capping, experiments in corer reactors showed that simulated tidal processes increased zinc fluxes 5- fold. Fluxes were also greater in the presence of sediment-dwelling organisms. If organisms were removed, and recolonising organisms later added, their bioturbation activities initially lowered zinc fluxes, but fluxes …
Clusterin Is An Extracellular Chaperone That Specifically Interacts With Slowly Aggregating Proteins On Their Off-Folding Pathway, Stephen Poon, T. M. Treweek, Mark R. Wilson, Simon B. Easterbrook-Smith, John A. Carver
Clusterin Is An Extracellular Chaperone That Specifically Interacts With Slowly Aggregating Proteins On Their Off-Folding Pathway, Stephen Poon, T. M. Treweek, Mark R. Wilson, Simon B. Easterbrook-Smith, John A. Carver
Faculty of Science - Papers (Archive)
Clusterin is an extracellular mammalian chaperone protein which inhibits stress-induced precipitation of many different proteins. The conformational state(s) of proteins that interact with clusterin and the stage(s) along the folding and off-folding (precipitation-bound) pathways where this interaction occurs were previously unknown. We investigated this by examining the interactions of clusterin with different structural forms of α-lactalbumin, γ-crystallin and lysozyme. When assessed by ELISA and native gel electrophoresis, clusterin did not bind to various stable, intermediately folded states of α-lactalbumin nor to the native form of this protein, but did bind to and inhibit the slow precipitation of reduced α-lactalbumin. Reduction-induced …
Synthesis Of (+/-)Epipentenomycin I And Iii, Weerachai Phutdhawong, Stephen G. Pyne, Apiwat Baramee, Duang Buddhasukh, Brian W. Skelton, Allan H. White
Synthesis Of (+/-)Epipentenomycin I And Iii, Weerachai Phutdhawong, Stephen G. Pyne, Apiwat Baramee, Duang Buddhasukh, Brian W. Skelton, Allan H. White
Faculty of Science - Papers (Archive)
A synthesis of (±) epipentenomycin I and III is reported from a regioselective epoxidation of racemic 3-hydroxy- and 3-acetoxy-2-methylene-4-cyclopentenone, respectively, with dimethyldioxirane followed by hydrolytic ring-opening of the resulting epoxide.
Mildly Acidic Ph Activates The Extracellular Molecular Chaperone Clusterin, Stephen Poon, M. S. Rybchyn, S. B. Easterbrook-Smith, J. A. Carver, G. J. Pankhurst, Mark R. Wilson
Mildly Acidic Ph Activates The Extracellular Molecular Chaperone Clusterin, Stephen Poon, M. S. Rybchyn, S. B. Easterbrook-Smith, J. A. Carver, G. J. Pankhurst, Mark R. Wilson
Faculty of Science - Papers (Archive)
Many features of the chaperone action of clusterin are similar to those of the intracellular small heat shock proteins (sHSPs) which, like clusterin, exist in solution as heterogeneous aggregates. Increased temperature induces dissociation of some sHSP aggregates and an enhanced chaperone action, suggesting that a dissociated form is the active chaperone species. We recently reported that clusterin aggregates dissociate at mildly acidic pH. To further explore the similarities between clusterin and the sHSPs, we tested the effects of temperature and pH on the structure of clusterin and its chaperone action. Our results demonstrate that increased temperature does not induce dissociation …
Detection Of P2x Purinergic Receptors On Human B Lymphocytes, Ronald Sluyter, J A. Barden, James Wiley
Detection Of P2x Purinergic Receptors On Human B Lymphocytes, Ronald Sluyter, J A. Barden, James Wiley
Faculty of Science - Papers (Archive)
B lymphocytes are known to synthesise the P2X(7) subtype of the P2X purinergic receptor family; however, the identification of the other six P2X subtypes on these cells has been limited by the absence of specific antibodies. In this study, we used a panel of anti-P2X polyclonal antibodies and confocal microscopy to examine the presence of each P2X receptor on human B lymphocytes. We observed that P2X(1), P2X(2), P2X(4) and P2X(7) subtypes, but not P2X(3), P2X(5) and P2X(6) subtypes, are present on B lymphocytes.
Enhanced Tumor Growth In Uv-Irradiated Skin Is Associated With An Influx Of Inflammatory Cells Into The Epidermis, Ronald Sluyter, Gary M. Halliday
Enhanced Tumor Growth In Uv-Irradiated Skin Is Associated With An Influx Of Inflammatory Cells Into The Epidermis, Ronald Sluyter, Gary M. Halliday
Faculty of Science - Papers (Archive)
UV radiation causes a number of cellular changes within the skin which play a role in tumor outgrowth, including immunosuppression and production of growth-enhancing cytokines, Both of these enable tumors to grow but their relative importance in carcinogenesis is poorly defined. In this study, C3H/HeN mice were exposed to a single inflammatory dose of 410 mJ/cm(2) UVB radiation (plus 100 mJ/cm2 UVA radiation) followed by the inoculation of a regressor squamous cell carcinoma into or the painting of oxazolone onto the treated skin. Tumors transplanted 2 or 3 but not 4 days after irradiation had a significantly higher growth rate …
Electrospray Ionisation Mass Spectrometry Of Ruthenium And Palladium Complexes With Oligonucleotides, Jennifer L. Beck, Amy Humphries, Margaret Sheil, Stephen F. Ralph
Electrospray Ionisation Mass Spectrometry Of Ruthenium And Palladium Complexes With Oligonucleotides, Jennifer L. Beck, Amy Humphries, Margaret Sheil, Stephen F. Ralph
Faculty of Science - Papers (Archive)
No abstract provided.
Synthesis Of Thiazole Analogues Of The Immunosuppressive Agent (1r,2s,3r)-2-Acetyl-4(5)-(1,2,3,4-Tetrahydroxybutyl)Imidazole, George R. Jeoffreys, Alison T. Ung, Stephen G. Pyne, Brian W. Skelton, Allan H. White
Synthesis Of Thiazole Analogues Of The Immunosuppressive Agent (1r,2s,3r)-2-Acetyl-4(5)-(1,2,3,4-Tetrahydroxybutyl)Imidazole, George R. Jeoffreys, Alison T. Ung, Stephen G. Pyne, Brian W. Skelton, Allan H. White
Faculty of Science - Papers (Archive)
The synthesis of four of the diastereoisomers of 2-acetyl-5-(1,2,3,4-tetrahydroxybutyl)thiazole and two of the diastereoisomers of 2-acetyl-5-(1,2,3,4,5-pentahydroxypentyl)thiazole and 2-acetyl-4-(1,2,3,4,5-pentahydroxypentyl)thiazole are reported. These syntheses involve the condensation of 5- or 4-metallated 2-(1,1-dimethoxyethyl)thiazoles with 2,3-O-isopropylidene-D-erythrono-1,4-lactone or 5-O-(tert-butyldimethylsilyl)-2,3-O-isopropylidene-D-ribonolactone followed by reductive ring-opening of the resulting lactols. The stereochemistries and structures of some key compounds have been determined by single crystal X-ray structural analysis.
[60]Fullerene Amino Acids And Related Derivatives, Glenn A. Burley, Paul A. Keller, Stephen G. Pyne
[60]Fullerene Amino Acids And Related Derivatives, Glenn A. Burley, Paul A. Keller, Stephen G. Pyne
Faculty of Science - Papers (Archive)
This paper is a review of the literature concerning the preparation of [60]fullerene amino acid and peptide derivatives. The structure and applications of these derivatives to the biological and material sciences is also presented.
Effect Of Organic Solvents On The Separation Of Benzoic Acids By Capillary Electrophoresis, Young J. Lee, William E. Price, Margaret Sheil
Effect Of Organic Solvents On The Separation Of Benzoic Acids By Capillary Electrophoresis, Young J. Lee, William E. Price, Margaret Sheil
Faculty of Science - Papers (Archive)
The effect of organic modifiers on the separation of a number of closely related isomeric benzoic acids by capillary electrophoresis is described. It is shown that while a single modifier concentration cannot help resolve the entire electropherogram, organic modifiers do significantly enhance the resolution of parts of the separation system by comparison with 40 mmol l-1 phosphate buffer. The effects on separation and retention times are discussed in terms of the effects on electroosmotic flow and the electrophoretic mobilities of the charged solutes. The effects were found to be modifier specific, although the trends were in the same direction (ie., …