Keryn Williams

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https://hdl.handle.net/2328/991
Professor Keryn Williams is a Principal Research Fellow in the School of Medicine at Flinders University. Her research interests include corneal transplantation, ocular inflammation, ocular immunology and eye banking.

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Browsing Keryn Williams by Subject "Australian Standard Research Classification 321016 Ophthalmology and Vision Science"

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    Apoptosis is a prominent feature of acute anterior uveitis in the Fischer 344 rat
    (BMJ Publishing Group - http://bjo.bmjjournals.com/, 2000-02) Smith, Justine R; Hart, Prue; Standfield, Scott D; Coster, Douglas John; Wing, Sarah J; Williams, Keryn Anne
    AIMS: To examine the hypothesis that apoptosis of infiltrating cells contributes to spontaneous resolution of uveitis in clinically relevant rodent models. METHODS: Experimental melanin induced uveitis (EMIU) was induced in Fischer 344 rats by immunisation with 250 microg bovine ocular melanin. Endotoxin induced uveitis (EIU) was induced by injection of 200 microg Escherichia coli lipopolysaccharide. Formalin fixed, paraffin embedded ocular cross sections were stained by terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate biotin nick end labelling (TUNEL) to identify apoptotic cells. Indirect immunoperoxidase staining of paraformaldehyde lysine periodate fixed tissue cross sections was used to demonstrate expression of inducible nitric oxide synthase (iNOS). RESULTS: TUNEL positive mononuclear cells were observed in the anterior uvea during both EMIU and EIU at all selected time points. However, whereas the majority of mononuclear cells appeared apoptotic from the outset of disease, neutrophils were notably TUNEL negative at all time points examined. Many infiltrating neutrophils expressed iNOS. CONCLUSION: Apoptosis occurs early in the course of rat EMIU and EIU, and may contribute to resolution of these diseases. In general, infiltrating mononuclear cells die rapidly, while neutrophils survive, producing inducible nitric oxide synthase which may contribute to disease pathogenesis.
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    The Australian Corneal Graft Registry 2004 annual report
    (2006-06-20T03:38:28Z) Williams, Keryn Anne; Hornsby, Ngaere B; Bartlett, Christine Mary; Holland, Helene K; Esterman, Adrian Jeffrey; Coster, Douglas John
    The Australian Corneal Graft Registry (ACGR) opened in May 1985 and has now been in operation for 18 years. In that time, we have collected data on over 14,000 corneal grafts. At the time of transplantation, we seek information on the recipient, the donor and the operative procedure. Follow-up then occurs at approximately yearly intervals for an indefinite period. Follow-up only ceases upon loss of the graft, or death or loss-to-follow-up of the patient. At each round of follow-up, we request information on graft and visual outcome, and upon relevant events and treatments. The data are entered into a database and checked for consistency. Descriptive, univariate and multivariate analyses are performed, and the report collated.
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    Corneal graft rejection occurs despite Fas ligand expression and apoptosis of infiltrating cells
    (BMJ Publishing Group - http://bjo.bmjjournals.com/, 2005-05) Williams, Keryn Anne; Standfield, Scott D; Smith, Justine R; Coster, Douglas John
    BACKGROUND/AIMS: Constitutive expression of Fas ligand (CD95L) protects the eye against cell mediated immune responses by inducing apoptosis in infiltrating Fas bearing T cells. This study was designed to examine Fas ligand expression on acutely rejecting rat corneal grafts and to investigate the kinetics of induction of apoptosis in infiltrating leucocytes. METHODS: Orthotopic penetrating corneal transplantation was performed between genetically disparate inbred rats. Fas ligand expression and the phenotype of infiltrating leucocytes were examined by immunohistochemistry. Apoptotic nuclei were visualised in sections of normal rat cornea, rejecting allografts, and time matched isografts by terminal deoxynucleotidyl transferase mediated dUTP biotin nick end labelling (TUNEL) and quantified by video image analysis. Staining with Hoechst dye 33258 was used to confirm the presence of apoptotic nuclei. RESULTS: Fas ligand was expressed on corneal endothelial and epithelial cells during acute corneal graft rejection. At all time points examined, including as early as the fifth postoperative day, the cells infiltrating both corneal isografts and allografts were TUNEL positive. By the 15th postoperative day, over 90% of all nuclei, many of which were T cells, were apoptotic. CONCLUSION: Expression of Fas ligand is not downregulated on the cornea during allograft rejection and infiltrating leucocytes in both isografts and allografts die rapidly in situ. Despite the death of the cells believed to be responsible for rejection, isografts survive indefinitely whereas allografts are irreparably damaged.
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    In vitro adenovirus mediated gene transfer to the human cornea
    (BMJ Publishing Group - http://bjo.bmjjournals.com/, 2005-06) Jessup, Claire Frances; Brereton, Helen Mary; Coster, Douglas John; Williams, Keryn Anne
    BACKGROUND/AIMS: Replication deficient adenovirus is an efficient vector for gene transfer to the cornea. The aim was to optimise the transduction of human corneal endothelium with adenoviral vectors and to measure transgene production from transduced corneas. METHODS: Adenoviral vectors (AdV) encoding enhanced green fluorescent protein (eGFP) or a transgenic protein (scFv) were used to transfect 34 human corneas. Reporter gene expression was assessed after 72-96 hours of organ culture. The kinetics of scFv production was monitored in vitro for 1 month by flow cytometric analysis of corneal supernatants. RESULTS: Transduction of human corneas with high doses (5 x 10(7)-3 x 10(8) pfu) of AdV caused eGFP expression in 12-100% of corneal endothelial cells. Corneas were efficiently transduced following up to 28 days in cold storage. Very high AdV doses (2 x 10(9) pfu) reduced endothelial cell densities to 98 (SD 129) nuclei/mm(2) (compared to 2114 (716) nuclei/mm(2) for all other groups). Transgenic protein production peaked at 2.4 (0.9) microg/cornea/day at 2 weeks post-transduction, and decreased to 1.2 (0.4) microg/cornea/day by 33 days, at which time endothelial cell density had decreased to 431 (685) nuclei/mm(2). CONCLUSION: Human corneas can be efficiently transduced by AdV following extended periods of cold storage, and transgene expression is maintained for at least 1 month in vitro.
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    Influence of advanced recipient and donor age on the outcome of corneal transplantation. Australian Corneal Graft Registry.
    (BMJ Publishing Group - http://bjo.bmjjournals.com/, 1997-10) Williams, Keryn Anne; Muehlberg, S M; Lewis, R F; Coster, Douglas John
    AIMS: The aims of this study were to examine the influence of advanced recipient and donor age on the long term outcome of corneal transplantation. METHODS: Records of 1036 penetrating corneal grafts in recipients aged > or = 80 years at surgery (defined as the elderly subset) and 8092 donor corneas used for transplantation were obtained from the Australian Corneal Graft Register database, Kaplan-Meier graft survival plots were compared using log rank statistics. RESULTS: Elderly recipients constituted 15% of the recipient pool. The major indication for corneal transplantation in the elderly was bullous keratopathy. Graft survival fell with increasing recipient age (p < 0.00001); the major cause of graft failure was rejection (33%). The desired outcome in 51% of cases was to improve vision and in 42% of cases to relieve pain; 23% of elderly recipients achieved a Snellen acuity of 6/18 or better in the grafted eye and 66% recorded improved acuity after transplantation. Elderly recipients suffered more complications and comorbidities in the grafted eye than did younger recipients. Donor age (stratified in 10 year intervals) did not influence corneal graft survival significantly (p = 0.10). CONCLUSIONS: Elderly graft recipients fared less well after corneal transplantation than did younger recipients, but outcomes in terms of long term graft survival and visual rehabilitation were still good. Donor age did not affect graft survival.
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    Influence of format on in vitro penetration of antibody fragments through porcine cornea
    (BMJ Publishing Group - http://bjo.bmjjournals.com/, 2005-09) Brereton, Helen Mary; Taylor, Susan D; Farrall, Alexandra L; Hocking, Dianna M; Thiel, Michael A; Tea, Melinda Nay; Coster, Douglas John; Williams, Keryn Anne
    AIM: Antibody fragments, appropriately formulated, can penetrate through the ocular surface and thus have potential as therapeutic agents. The aim was to investigate the influence of protein fragment format on the kinetics and extent of ocular penetration in vitro. METHODS: Immunoglobulin single chain variable domain fragments of a murine monoclonal antibody with specificity for rat CD4 were engineered with a 20 or 11 amino acid linker by assembly polymerase chain reaction, expressed in Escherichia coli and purified by chromatography. Fab fragments of the parental antibody were prepared by papain digestion. Antibody fragments were formulated with a penetration and a viscosity enhancer and were applied to the surface of perfused pig corneas for up to 10 hours in vitro. Penetration was quantified by flow cytometry on rat thymocytes. RESULTS: 20-mer antibody fragments formed natural monomers and dimers following purification that could be separately isolated, while 11-mer fragments were dimeric. All formats of fragment (20-mer monomers and dimers, 11-mer dimers, Fab) showed penetration through the pig cornea after 6 hours of intermittent topical administration. CONCLUSION: Antibody fragments of different shapes and sizes can penetrate the cornea after topical administration, thereby increasing the potential of this class of proteins for topical ophthalmic use.
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    The long term outcome of limbal allografts: the search for surviving cells
    (BMJ Publishing Group - http://bjo.bmjjournals.com/, 2001-05) Henderson, Timothy R; Coster, Douglas John; Williams, Keryn Anne
    BACKGROUND/AIMS: Limbal allotransplantation is increasingly being used for ocular surface repair in patients with limbal stem cell dysfunction. However, it is uncertain whether donor cells survive long term on the ocular surface and whether patients maintain the early benefits of the procedure. The aims of this study were to investigate the long term outcome of clinical limbal allografts and to correlate outcome with donor cell survival. METHODS: Five patients who had undergone allotransplantation-four keratolimbal allografts and one tarsoconjunctival allograft-from 3-5 years previously, and for whom residual frozen donor ocular tissue was available, were reviewed. Survival of donor cells lifted from the recipient ocular surface by impression cytology was investigated by DNA fingerprinting using primers detecting variable nucleotide tandem repeat sequences. Recipient buccal cells and scleral samples from the remnant donor eye were used to genotype recipients and donors, respectively. Polymerase chain reaction products were sized by Genescan analysis. RESULTS: An objective long term benefit from the procedure (improved Snellen acuity, reduced frequency of epithelial defects, reduced vascularisation, and scarring) was recorded for four patients. Some subjective benefit was also reported. However, in no instances were donor cells recovered from the ocular surface at 3-5 years post-graft. Initial experiments to examine sensitivity indicated that any surviving donor cells must have constituted less than 2.5% of cells sampled. CONCLUSION: Limbal stem cell allotransplantation can provide long term benefits, as measured by objective criteria. However, such benefits do not necessarily correlate with survival of measurable numbers of donor cells on the ocular surface.
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    A simple corneal perfusion chamber for drug penetration and toxicity studies
    (BMJ Publishing Group - http://bjo.bmjjournals.com/, 2001-04) Thiel, Michael A; Morlet, N; Schulz, D; Edelhauser, HF; Dart, JK; Coster, Douglas John; Williams, Keryn Anne
    AIMS: Corneal perfusion chambers are important tools in the development and assessment of ophthalmic drugs. The aim of this study was to design and test a modified perfusion chamber suitable for topical application of drugs to isolated corneoscleral preparations, and which allowed continuous monitoring of endothelial cell function. METHODS: A polycarbonate and stainless steel perfusion chamber was designed to clamp corneas in a horizontal plane suitable for topical drug delivery. Endothelial cell function was assessed by ultrasonic pachymetry and specular microscopy during perfusion. Epithelial barrier function was assessed by penetration of fluorescein. Leakage was examined by measuring penetration of a large protein, IgG. Tissue architecture after perfusion was examined by conventional histology. RESULTS: Corneas maintained a functionally and morphologically intact endothelial monolayer during perfusion periods of up to 14 hours. The epithelial barrier function was well preserved. The tissue clamp sealed the preparation effectively against leakage of macromolecules. CONCLUSION: The new chamber device forms a reliable tool for in vitro drug penetration and toxicity studies in isolated perfused corneoscleral tissue.