Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

2004

PDF

CMMB

Articles 1 - 20 of 20

Full-Text Articles in Life Sciences

Intranasal Vaccination With Streptococcal Fibronectin Binding Protein Sfb1 Fails To Prevent Growth And Dissemination Of Streptococcus Pyogenes In A Murine Skin Infection Model, Jason D. Mcarthur, E. Medina, J. Chin, B. J. Currie, K. S. Sriprakash, S. R. Talay, G. S. Chhatwal, Mark J. Walker Dec 2004

Intranasal Vaccination With Streptococcal Fibronectin Binding Protein Sfb1 Fails To Prevent Growth And Dissemination Of Streptococcus Pyogenes In A Murine Skin Infection Model, Jason D. Mcarthur, E. Medina, J. Chin, B. J. Currie, K. S. Sriprakash, S. R. Talay, G. S. Chhatwal, Mark J. Walker

Faculty of Science - Papers (Archive)

Fibronectin binding protein F1 (Sfb1) of Streptococcus pyogenes (group A streptococcus [GAS]) is a well-characterized adhesin that has been shown to induce protection in mice against a lethal intranasal GAS challenge after intranasal immunization with cholera toxin B subunit (CTB) as adjuvant. With a murine skin infection model, we have shown that Sfb1/CTB vaccination neither elicits opsonizing antibodies nor prevents systemic bacterial growth and dissemination to internal organs after a subcutaneous GAS challenge. These results indicate that an Sfb1-based vaccine should be complemented with additional protective antigens in order to be used in areas such as the tropical north ...


Two Distinct Genotypes Of Prtf2, Encoding A Fibronectin Binding Protein, And The Evolution Of The Gene Family In Streptococcus Pyogenes, V. Ramachandran, Jason D. Mcarthur, C. E. Behm, C. Gutzeit, M. Dowton, P. K. Fagan, R. Towers, B. J. Currie, K. S. Sriprakash, Mark J. Walker Nov 2004

Two Distinct Genotypes Of Prtf2, Encoding A Fibronectin Binding Protein, And The Evolution Of The Gene Family In Streptococcus Pyogenes, V. Ramachandran, Jason D. Mcarthur, C. E. Behm, C. Gutzeit, M. Dowton, P. K. Fagan, R. Towers, B. J. Currie, K. S. Sriprakash, Mark J. Walker

Faculty of Science - Papers (Archive)

The group A Streptococcus (GAS) is an important pathogen responsible for a wide range of human diseases. Fibronectin binding proteins (FBPs) play important role in promoting GAS adherence and invasion of host cells. The gene prtF2 encodes a FBP and is contained in approximately 60% of GAS strains. In the present study we have examined 51 prtF2-positive GAS strains isolated from the Northern Territory of Australia and describe two genotypes of prtF2, which are mutually exclusive. Both genotypes have been previously identified in the literature as pfbp and fbaB. We show these genotypes map to the same chromosomal location within ...


Protecting Group Effects On The Efficiency Of The Ruthenium-Catalyzed Alder-Ene Reaction, Joseph Hartley, Stephen G. Pyne Jan 2004

Protecting Group Effects On The Efficiency Of The Ruthenium-Catalyzed Alder-Ene Reaction, Joseph Hartley, Stephen G. Pyne

Faculty of Science - Papers (Archive)

The efficiency of the ruthenium-catalysed Alder-ene reaction of hydroxy alkenes depends heavily on the nature of the O-protecting groups employed as well as the length of the carbon spacer between the hydroxy and alkene group.


Molecular Dynamics Simulations Of Peptides Containing An Unnatural Amino Acid: Dimerization, Folding, And Protein Binding, Haibo Yu, Xavier Daura, Wilfred Van Gunsteren Jan 2004

Molecular Dynamics Simulations Of Peptides Containing An Unnatural Amino Acid: Dimerization, Folding, And Protein Binding, Haibo Yu, Xavier Daura, Wilfred Van Gunsteren

Faculty of Science - Papers (Archive)

We have performed molecular dynamics (MD) simulations to study the dimerization, folding, and binding to a protein of peptides containing an unnatural amino acid. NMR studies have shown that the substitution of one residue in a tripeptide β-strand by the unnatural amino acid Hao (5-HO2CCONH-2-MeO-C6H3-CO-NHNH2) modifies the conformational flexibility of the β-strand and the hydrogen-bonding properties of its two edges: The number of hydrogen-bond donors and acceptors increases at one edge, whereas at the other, they are sterically hindered. In simulations in chloroform, the Hao-containing peptide 9 (i-PrCO-Phe-Hao-Val-NHBu) forms a β-sheet–like hydrogen-bonded dimer, in good agreement with the available ...


On The Transferability Of The Spcal Water Model To Biomolecular Simulation, Alice Glaettli, Chris Oostenbrink, Xavier Daura, Daan Geerke, Haibo Yu, Wilfred Van Gunsteren Jan 2004

On The Transferability Of The Spcal Water Model To Biomolecular Simulation, Alice Glaettli, Chris Oostenbrink, Xavier Daura, Daan Geerke, Haibo Yu, Wilfred Van Gunsteren

Faculty of Science - Papers (Archive)

We investigated the performance of the recently developed SPC/L model for liquid water, as a pure liquid, in binary mixtures with DMSO, and as a solvent model in a peptide folding simulation. Additionally, in order to test the compatibility with the GROMOS biomolecular force field, free energies of hydration of a set of representative compounds were computed. The results are compared to those for the well established SPC water model, which is generally used as a solvent model in conjunction with the GROMOS force field already for more than two decades. It turns out that as a pure liquid ...


Processes Controlling Metal Transport And Retention As Metal-Contaminated Groundwaters Efflux Through Estuarine Sediments, Stuart L. Simpson, Edward J. Maher, Dianne F. Jolley Jan 2004

Processes Controlling Metal Transport And Retention As Metal-Contaminated Groundwaters Efflux Through Estuarine Sediments, Stuart L. Simpson, Edward J. Maher, Dianne F. Jolley

Faculty of Science - Papers (Archive)

Factors affecting the transport and retention of Cd, Cr, Cu, Ni, Pb and Zn in acidic groundwaters as they pass through estuarine sediments were investigated using column experiments. Acidic groundwaters caused the rapid dissolution of iron sulfide (AVS) and other iron and manganese phases from sediments that are important for metal binding and buffering. Metal breakthrough to overlying water occurred in the order of Ni>Zn>Cd>>Cu>>Cr/Pb. Metal transport increased as the sediment permeability increased, reflecting the low resistance to flow caused by larger sand-sized particles and the decreased abundance of metal adsorption sites on these materials ...


Synthesis Of (+)-(1r,2s,9s,9ar)-Octahydro-1h-Pyrrolo-[1,2-A]Azepine-1,2,9-Triol: A Potential Glycosidase Inhibitor, Karl B. Lindsay, Stephen G. Pyne Jan 2004

Synthesis Of (+)-(1r,2s,9s,9ar)-Octahydro-1h-Pyrrolo-[1,2-A]Azepine-1,2,9-Triol: A Potential Glycosidase Inhibitor, Karl B. Lindsay, Stephen G. Pyne

Faculty of Science - Papers (Archive)

The title compound was prepared as a potential glycosidase inhibitor. Key steps in the synthesis are vinyl epoxide aminolysis, ring-closing metathesis, cis-dihydroxylation and then ring closure.


Phytochemical And Larvicidal Studies On Stemona Curtisii: Structure Of A New Pyriodo[1,2-A]Azepine Stemona Alkaloid, Pitchaya Mungkornasawakul, Stephen G. Pyne, Araya Jatisatienr, Damrat Supyen, Chaiwat Jatisatienr, Wilford Lie, Alison T. Ung, Brian W. Skelton, Allan H. White Jan 2004

Phytochemical And Larvicidal Studies On Stemona Curtisii: Structure Of A New Pyriodo[1,2-A]Azepine Stemona Alkaloid, Pitchaya Mungkornasawakul, Stephen G. Pyne, Araya Jatisatienr, Damrat Supyen, Chaiwat Jatisatienr, Wilford Lie, Alison T. Ung, Brian W. Skelton, Allan H. White

Faculty of Science - Papers (Archive)

A new pentacyclic Stemona alkaloid, stemocurtisinol (3), with a pyrido[1,2-a]azepine A,B-ring system, and the known pyrrolo[1,2-a]azepine alkaloid oxyprotostemonine (4) have been isolated from a root extract of S. curtisii. The structure and relative stereochemistry of stemocurtisinol was determined by spectral data interpretation and X-ray crystallography. This compound is a diastereoisomer of oxystemokerrin and has the opposite configuration at C-4 and C-19. The individual alkaloid components showed significant larvicidal activity (IC50 4−39 ppm) on mosquito larvae (Anopheles minimus HO).


Asymmetric Synthesis Of (+)-1-Epiaustraline And Attempted Synthesis Of Australine, Minyan Tang, Stephen G. Pyne Jan 2004

Asymmetric Synthesis Of (+)-1-Epiaustraline And Attempted Synthesis Of Australine, Minyan Tang, Stephen G. Pyne

Faculty of Science - Papers (Archive)

A diastereoselective synthesis of the pyrrolizidine alkaloid, (+)-1-epiaustraline has been achieved via a diastereoselective syn-dihydroxylation of a pyrrolo[1,2-c]oxazol-3-one precursor that was readily prepared by a RCM reaction. Attempts to extend this methodology to the synthesis of australine were not successful since the final pyrrolidine ring closure to produce the desired pyrrolizidine of the target molecule was not productive.


Asymmetric Synthesis Of (-)-Swainsonine, Karl Lindsay, Stephen G. Pyne Jan 2004

Asymmetric Synthesis Of (-)-Swainsonine, Karl Lindsay, Stephen G. Pyne

Faculty of Science - Papers (Archive)

This paper describes a new synthesis of (-)-swainsonine via the ring-closing metathesis reaction of a substituted 3-allyl-4-vinyl-2-oxazolindinone and subsequent diastereoselective syn-dihydroxylation of the resulting pyrrolo[1,2-c]oxazol-3-one.


Studies On The Synthesis Of Croomine: Synthesis Of The Tricyclic B,C,D-Ring Core Structure, Karl B. Lindsay, Stephen G. Pyne Jan 2004

Studies On The Synthesis Of Croomine: Synthesis Of The Tricyclic B,C,D-Ring Core Structure, Karl B. Lindsay, Stephen G. Pyne

Faculty of Science - Papers (Archive)

A convergent and asymmetric synthesis of the tricyclic B,C,D-ring core structure of croomine has been achieved, using aminolysis reactions of chiral vinyl epoxides and the RCM reaction.


Phytochemical Studies On Stemona Burkillii Prain: Two New Dihydrostemofoline Alkaloids, Pitchaya Mungkornasawakul, Stephen G. Pyne, Araya Jatisatienr, Wilford Lie, Alison T. Ung, Kritchaya Issakul, Auntika Sawatwanich, Damrat Supyen, Chaiwat Jatisatienr Jan 2004

Phytochemical Studies On Stemona Burkillii Prain: Two New Dihydrostemofoline Alkaloids, Pitchaya Mungkornasawakul, Stephen G. Pyne, Araya Jatisatienr, Wilford Lie, Alison T. Ung, Kritchaya Issakul, Auntika Sawatwanich, Damrat Supyen, Chaiwat Jatisatienr

Faculty of Science - Papers (Archive)

Two new dihydrostemofoline alkaloids, 11(S),12(R)-dihydrostemofoline (3) and stemoburkilline (4), along with stemofoline (1) and 2’-hydroxystemofoline (2) have been isolated from a root extract of Stemona burkillii Prain. The structure and relative configuration of (3) have been determined via spectroscopic data and from comparison with synthetic 11(S),12(S)-dihydrostemofoline (5). The configuration of the exo-cyclic alkene group in (4) is tentively assigned as (E) based upon mechanistic considerations.


Asymmetric Synthesis Of Polyfunctionalized Pyrrolidines And Related Alkaloids, Stephen G. Pyne, Andrew S. Davis, Nicole Gates, Joseph Hartley, Karl Lindsay, Theeraphan Machan, Minyan Tang Jan 2004

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 Jan 2004

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 ...


Charge-On-Spring Polarizable Water Models Revisited: From Water Clusters To Liquid Water To Ice, Haibo Yu, Wilfred Van Gunsteren Jan 2004

Charge-On-Spring Polarizable Water Models Revisited: From Water Clusters To Liquid Water To Ice, Haibo Yu, Wilfred Van Gunsteren

Faculty of Science - Papers (Archive)

The properties of two improved versions of charge-on-spring �COS� polarizable water models (COS/G2 and COS/G3) that explicitly include nonadditive polarization effects are reported. In COS models, the polarization is represented via a self-consistently induced dipole moment consisting of a pair of separated charges. A previous polarizable water model (COS/B2), upon which the improved versions are based, was developed by Yu, Hansson, and van Gunsteren �J. Chem. Phys. 118, 221 �2003��. To improve the COS/B2 model, which overestimated the dielectric permittivity, one additional virtual atomic site was used to reproduce the water monomer quadrupole moments besides the ...


The Development Of Signal Transduction Pathways During Epididymal Maturation Is Calcium Dependent, Heath W. Ecroyd, Kelly Asquith, Russell C. Jones, Robert J. Aitken Jan 2004

The Development Of Signal Transduction Pathways During Epididymal Maturation Is Calcium Dependent, Heath W. Ecroyd, Kelly Asquith, Russell C. Jones, Robert J. Aitken

Faculty of Science - Papers (Archive)

Capacitation has been correlated with the activation of a cAMP-PKA-dependent signaling pathway leading to protein tyrosine phosphorylation. The ability to exhibit this response to cAMP matures during epididymal maturation in concert with the ability of the sperrnatozoa to capacitate. In this study, we have addressed the mechanisms by which spermatozoa gain the potential to activate this signaling pathway during epididymal maturation. In a modified Tyrode's medium containing 1.7 mM calcium, caput spermatozoa had significantly higher [Ca2+](i) than caudal cells and could not tyrosine phosphorylate in response to cAMP. However, in calcium-depleted medium both caput and caudal cells ...


Analysis Of The Mechanism By Which Calcium Negatively Regulates The Tyrosine Phosphorylation Cascade Associated With Sperm Capacitation, Mark Baker, Louise Hethrington, Heath W. Ecroyd, Shaun D. Roman, Robert J. Aitken Jan 2004

Analysis Of The Mechanism By Which Calcium Negatively Regulates The Tyrosine Phosphorylation Cascade Associated With Sperm Capacitation, Mark Baker, Louise Hethrington, Heath W. Ecroyd, Shaun D. Roman, Robert J. Aitken

Faculty of Science - Papers (Archive)

The capacitation of mammalian spermatozoa involves the activation of a cAMP-mediated signal transduction pathway that drives tyrosine phosphorylation via mechanisms that are unique to this cell type. Controversy surrounds the impact of extracellular calcium on this process, with positive and negative effects being recorded in independent publications. We clearly demonstrate that the presence of calcium in the external medium decreases tyrosine phosphorylation in both human and mouse spermatozoa. Under these conditions, a rise in intracellular pH was recorded, however, this event was not responsible for the observed changes in phosphotyrosine expression. Rather, the impact of calcium on tyrosine phosphorylation in ...


Compartmentalization Of Prion Isoforms Within The Reproductive Tract Of The Ram, Heath W. Ecroyd, Pierre Sarradin, Jean-Louis Dacheux, Jean-Luc Gatti Jan 2004

Compartmentalization Of Prion Isoforms Within The Reproductive Tract Of The Ram, Heath W. Ecroyd, Pierre Sarradin, Jean-Louis Dacheux, Jean-Luc Gatti

Faculty of Science - Papers (Archive)

Cellular prion protein (Prp(C)) is a glycoprotein usually associated with membranes via its glycosylphosphatidylinositol (GPI) anchor. The trans-conformational form of this protein (Prp(SC)) is the suggested agent responsible for transmissible neurodegenerative spongiform encephalopathies. This protein has been shown on sperm and in the reproductive fluids of males. Antibodies directed against the C-terminal sequence near the GPI-anchor site, an N-terminal sequence, and against the whole protein showed that the Prp isoforms were compartmentalized within the reproductive tract of the ram. Immunoblotting with the three antibodies showed that the complete protein and both N- and C-terminally truncated and glycosylated isoforms ...


Metal Equilibration And Bioavailability In Laboratory-Contaminated (Spiked) Sediments Used For The Development Of Whole-Sediment Toxicity Tests, Stuart L. Simpson, Brad M. Angel, Dianne F. Jolley Jan 2004

Metal Equilibration And Bioavailability In Laboratory-Contaminated (Spiked) Sediments Used For The Development Of Whole-Sediment Toxicity Tests, Stuart L. Simpson, Brad M. Angel, Dianne F. Jolley

Faculty of Science - Papers (Archive)

The equilibration and bioavailability of metals in laboratory-contaminated sediments has been investigated in order to provide better guidance on acceptable procedures for spiking sediments with metals for use in the development whole-sediment toxicity tests. The equilibration rates of Cd, Cu, Ni and Zn spiked into three estuarine surface sediments with varying properties were investigated. Changes to sediment pH, redox potential, porewater and acid soluble metals, acid-volatile sulfide and bacterial activity during equilibration, effects of temperature and disturbances following equilibration are reported. The addition of metals to sediments caused major decreases in pH and increases in redox potential as metals displaced ...


Selenium Accumulation In The Cockle Anadara Trapezia, Dianne F. Jolley, William A. Maher, Jennelle Kyd Jan 2004

Selenium Accumulation In The Cockle Anadara Trapezia, Dianne F. Jolley, William A. Maher, Jennelle Kyd

Faculty of Science - Papers (Archive)

An extensive study on Se accumulation in a population of Anadara trapezia from a marine lake is reported. The effects of organism mass, gender, reproductive cycle, and season on Se accumulation and tissue distribution were investigated. Analyses showed that gender and reproductive cycle had no significant effect on Se accumulation. A. trapezia showed a strong positive correlation between Se burden and tissue mass. Constant Se concentrations were observed within individual populations but varied spatially with sediment Se concentrations. Se concentrations in tissues decreased from gills>gonad/intestineOmantleO muscleOfoot, which remained constant over 12 months, however, significantly lower concentrations were observed ...