ORCID Profile
0000-0001-7352-1112
Current Organisation
The University of Auckland
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/CH13452
Abstract: We report the multistep synthesis and polymerisation of a novel aniline derivative with a pendant α-d-mannose substituent. The α-D-mannose functionality was successfully introduced before polymerisation via copper-catalysed azide alkyne click chemistry and the resulting monomer was polymerised using general oxidative polymerisation conditions, producing a water soluble mannosylated polyaniline. The polymer was characterised by several techniques and compared with standard polyaniline. The selective binding of the polymer to Concanavalin A (ConA) was successfully demonstrated by the precipitation of polymer–ConA aggregates. Potential applications of these novel polyaniline glycopolymers could include the development of electroactive biomaterials with the ability to bind mannose receptors, or as sensors for proteins or microbes.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0SC01814G
Abstract: We herein report the synthesis and biological and computational evaluation of 12 linear analogues of the cyclic lipopeptide battacin, enabled by Cysteine Lipidation on a Peptide or Amino Acid (CLipPA) technology.
Publisher: Springer Science and Business Media LLC
Date: 24-08-2014
DOI: 10.1007/S00455-014-9558-1
Abstract: Citric acid is used in cough reflex testing in clinical and research settings to assess reflexive cough in patients at risk of swallowing disorders. To address a lack of knowledge in this area, this study investigated the stability and sterility of citric acid solutions. Triplicate solutions of citric acid (0.8 M) in isotonic saline were stored at 4 ± 2 °C for up to 28 days and analysed by high-performance liquid chromatography. Microbiological sterility of freshly prepared s les and bulk s les previously used for 2 weeks within the hospital was determined using a pour plate technique. Microbial survival in citric acid was determined by inoculating Staphylococcus aureus, Escherichia coli, or Candida albicans into citric acid solution and monitoring the number of colony-forming units/mL over 40 min. Citric acid solutions remained stable at 4 °C for 28 days (98.4 ± 1.8 % remained). The freshly prepared and clinical s les tested were sterile. However, viability studies revealed that citric acid solution allows for the survival of C. albicans but not for S. aureus or E. coli. The microbial survival study showed that citric acid kills S. aureus and E. coli but has no marked effect on C. albicans after 40 min. Citric acid s les at 0.8 M remained stable over the 4-week testing period, with viable microbial cells absent from s les tested. However, C. albicans has the ability to survive in citric acid solution if inadvertently introduced in practice. For this reason, in clinical and research practice it is suggested to use single-use aliquots prepared aseptically which can be stored for up to 28 days at 4 °C.
Publisher: MDPI AG
Date: 18-12-2020
DOI: 10.3390/MOLECULES25245997
Abstract: We have isolated a filamentous fungus that actively secretes a pigmented exudate when growing on agar plates. The fungus was identified as being a strain of Epicoccum nigrum. The fungal exudate presented strong antifungal activity against both yeasts and filamentous fungi, and inhibited the germination of fungal spores. The chemical characterization of the exudate showed that the pigmented molecule presenting antifungal activity is the disalt of epipyrone A—a water-soluble polyene metabolite with a molecular mass of 612.29 and maximal UV–Vis absorbance at 428 nm. This antifungal compound showed excellent stability to different temperatures and neutral to alkaline pH.
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.WATRES.2018.01.018
Abstract: The cyanotoxins released into waters during cyanobacterial blooms can pose serious hazards to humans and animals. Apart from their toxicological mechanisms, cyanotoxins have been shown to be involved in estrogenic activity by in vivo and in vitro assays however, there is limited information on the change in estrogenicity of cyanotoxins following chemical oxidation. In this study, the estrogenic activity of cylindrospermopsin (CYL) and anatoxin-a (ANA) at concentrations ranging from 2.4 × 10
Publisher: Wiley
Date: 03-2011
DOI: 10.1111/J.1442-9071.2010.02471.X
Abstract: A prototype solid-state Ultraviolet-C (UVC) LED device may be useful in the treatment of corneal microbial infections, as UVC is commonly used for eradicating bacteria, fungi and viruses in other settings. This study assessed the efficacy of 265 nm UVC from this LED, on four different bacterial strains, and investigated the consequences of corresponding exposures on human corneal epithelial cells in vitro. Agar plate lawns of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Streptococcus pyogenes were exposed to a 4.5 mm diameter 265 nm UVC beam at a fixed intensity and distance, for 30, 5, 4, 2 and 1 seconds. Growth inhibition was assessed with a BioRad Gel imager, and the diameter of lucent areas of bacterial inhibition recorded. Human corneal epithelial cells cultured on glass cover-slips were exposed to corresponding doses of UVC from the same device. Live/dead staining was performed and the results quantified. There was 100% inhibition of growth for all bacteria tested, at all exposure times. A 30-second exposure of human corneal epithelium to UVC gave no statistically significant decrease (P = 0.877) in the ratio of live to dead cells when compared to control cultures. The results confirmed that a 1 second exposure to germicidal UVC from this LED source was sufficient to inhibit microbial proliferation in the four bacterial strains tested in vitro. The literature suggests UVC at this dose could potentially be beneficial in treating corneal surface infections, without causing significant adverse effects, supported by our findings in human corneal epithelium exposed to UVC.
Publisher: The Company of Biologists
Date: 11-2011
DOI: 10.1242/DMM.006122
Abstract: Inflammatory bowel disease (IBD), in the form of Crohn’s disease (CD) or ulcerative colitis (UC), is a debilitating chronic immune disorder of the intestine. A complex etiology resulting from dysfunctional interactions between the intestinal immune system and its microflora, influenced by host genetic susceptibility, makes disease modeling challenging. Mutations in NOD2 have the highest disease-specific risk association for CD, and a related gene, NOD1, is associated with UC. NOD1 and NOD2 encode intracellular bacterial sensor proteins acting as innate immune triggers, and represent promising therapeutic targets. The zebrafish has the potential to aid in modeling genetic and environmental aspects of IBD pathogenesis. Here, we report the characterization of the Nod signaling components in the zebrafish larval intestine. The nod1 and nod2 genes are expressed in intestinal epithelial cells and neutrophils together with the Nod signaling pathway genes ripk2, a20, a , cd147, centaurin b1, erbin and grim-19. Using a zebrafish embryo Salmonella infection model, morpholino-mediated depletion of Nod1 or Nod2 reduced the ability of embryos to control systemic infection. Depletion of Nod1 or Nod2 decreased expression of dual oxidase in the intestinal epithelium and impaired the ability of larvae to reduce intracellular bacterial burden. This work highlights the potential use of zebrafish larvae in the study of components of IBD pathogenesis.
Publisher: Elsevier BV
Date: 03-2010
DOI: 10.1016/J.DCI.2009.11.007
Abstract: Cxcl8 is a pro-inflammatory chemokine, best known for its role in neutrophil chemotaxis. Signalling through its receptors, Cxcr1 and Cxcr2, is induced by inflammatory stimuli evoked by microbial, chemical or environmental stress, and hormonal signals. While it is recognised that Cxcl8 signalling is active in the gut mucosa, this is not as well understood as its role in leukocyte trafficking. Here, we report the characterisation of genes encoding the zebrafish Cxcl8, Cxcr1 and Cxcr2. By a combination of genomic, expression and functional analyses, we show that the Cxcl8 signalling pathway is conserved in zebrafish. As in humans, cxcl8 is expressed in zebrafish leukocytes. Transcripts were also detected in intestinal epithelial cells, and this expression is upregulated under inflammatory conditions caused by bacterial or chemical insult. Expression of cxcr1 and cxcr2 is robust within the developing gut. This work provides a model for the study of Cxcl8 signalling during gut inflammation.
Publisher: Wiley
Date: 27-05-2020
Publisher: Elsevier BV
Date: 07-2022
DOI: 10.1016/J.JTOS.2022.05.004
Abstract: Preclinical evaluation of the therapeutic potential of antimicrobial 265 nm UVC for infectious keratitis. Four experiments explored UVC: 1) impact on bacterial and fungal lawns on agar, in in idual or mixed culture, 2) bacterial inactivation dose in an in vitro deep corneal infection model, 3) dose validation in an ex vivo porcine keratitis model and 4) efficacy in a masked, randomised, controlled murine keratitis trial using bioluminescent Pseudomonas aeruginosa. Minimum effective UVC exposures ranged between 2 s and 5 s for lawn bacteria and fungi in in idual or mixed culture. Significant P. aeruginosa growth inhibition in the in vitro infection model was achieved with 15 s UVC, that resulted in a >3.5 log UVC inhibited all tested bacteria and fungi, including mixed culture and strains linked to antibiotic resistance, in vitro, with exposures of ≤ 5 s. In vitro and ex vivo testing confirmed therapeutic potential of 15 s UVC. In vivo, 15 s UVC administered in two doses, 4 h apart, proved effective in treating murine bacterial keratitis.
Publisher: Elsevier BV
Date: 04-2021
Publisher: Informa UK Limited
Date: 02-2013
DOI: 10.2147/OPTH.S40680
Publisher: Elsevier
Date: 2001
DOI: 10.1016/S0065-2911(01)45005-3
Abstract: The discovery that bacterial cells can communicate with each other has led to the realization that bacteria are capable of exhibiting much more complex patterns of co-operative behaviour than would be expected for simple unicellular microorganisms. Now generically termed 'quorum sensing', bacterial cell-to-cell communication enables a bacterial population to mount a unified response that is advantageous to its survival by improving access to complex nutrients or environmental niches, collective defence against other competitive microorganisms or eukaryotic host defence mechanisms and optimization of population survival by differentiation into morphological forms better adapted to combating environmental threats. The principle of quorum sensing encompasses the production and release of signal molecules by bacterial cells within a population. Such molecules are released into the environment and, as cell numbers increase, so does the extracellular level of signal molecule, until the bacteria sense that a threshold has been reached and gene activation, or in some cases depression or repression, occurs via the activity of sensor-regulator systems. In this review, we will describe the biochemistry and molecular biology of a number of well-characterized N-acylhomoserine lactone quorum sensing systems to illustrate how bacteria employ cell-to-cell signalling to adjust their physiology in accordance with the prevailing high-population-density environment.
Location: New Zealand
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Simon Swift.