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Biomedical subjects

Brendan Vote

Publications and source records attributed to Brendan Vote.

9 recordsLinked to original sources
PubMed2005

An experimental method for testing novel retinal vital stains.

There is uncertainty surrounding the safety of the vital stains currently used to assist macular surgery, and there may be other agents that are more suitable. This study aimed to validate a method of screening retinal vital stains for their potential surgical utility. Bovine retina was exposed to test agents at a range of concentrations. Masked observers determined the minimum dye concentration that reliably stained the retina, defined as the minimum visible concentration (MVC). Computer image analysis (CIE94 colour difference equation) was used to estimate the magnitude of the colour difference between stained and unstained retina. Agents that had favourable staining characteristics underwent safety testing using a retinal pigment epithelium and glial cell culture model. Cells were exposed to each agent and viability was assessed with a mitochondrial enzyme (MTT) assay, and fluorescent live-dead probe (ethidium homodimer-1/calcein-AM). Frozen sections were used to determine which retinal layers were stained. Techniques were tested on the following agents: alcian blue; diethyloxadicarbocyanine; Evan's blue; fast green; fluorescein; Janus green; methylene blue; naphthol green; neutral red; procian (reactive) yellow; rose bengal; and trypan blue. For most dyes, the results of image analysis showed that colour differences increased linearly with dye concentration, although some displayed a more exponential relationship. Five agents showed favourable staining characteristics: Evan's blue, rose bengal, naphthol green, neutral red, and trypan blue (MVC 0.02, 0.01, 0.1, 0.002, 0.01%, respectively). Safety testing of these five agents did not show toxicity, except in glial cells exposed to rose bengal. Relative to the negative control (saline), these showed a 48% reduction in viability using the MTT assay (p<0.001; t=4.71; CI 30-75%), and qualitative damage on fluorescence microscopy. Frozen sections showed that some agents produced diffuse staining of all retinal layers, others produced selective inner retinal staining. There are thousands of biological stains available and many of these may be more effective or safer than those currently used for retinal surgery. This study provides a means of screening potentially useful vital stains.

Animals↗
PubMed2004

Systemic anti-inflammatory fibrosis suppression in threatened trabeculectomy failure.

PURPOSE: To provide a rationale for the use of systemic anti-inflammatory fibrosis suppression in the postoperative management of threatened early trabeculectomy bleb failure. METHODS: A review of the literature and of the authors' own experiences was conducted. RESULTS: The most important cause of persistent elevation of intraocular pressure after trabeculectomy is unduly marked or persistent inflammation with deposition of fibrous tissue, which prevents the formation of an adequately draining bleb. It was found that a clinically useful degree of suppression of bleb inflammation and fibrosis can be obtained with a 4-6 week course of the combined systemic administration of prednisone (10 mg t.i.d.), a non-steroidal anti-inflammatory agent (e.g. diclofenac 100 mg SR daily) and colchicine (0.25 mg or 0.3 mg t.i.d.), which was termed anti-inflammatory fibrosis suppression. Topical atropine 1% t.i.d. and adrenaline 1% t.i.d. eye drops can also be considered in addition to routine postoperative topical steroids. CONCLUSIONS: Despite advances in surgical techniques and methods to control fibrosis, anti-inflammatory fibrosis suppression is a valuable tool to have available in the post-operative period for management of trabeculectomies that threaten failure. This regime produces a diffuse bleb, which has a very low risk of late infection or bleb perforation. It is recommend that this regime be added to the list of therapies that are considered when clinical features suggestive of a failing bleb are confronted early in the post-operative course.

Anti-Inflammatory Agents↗
PubMed2004

Safety testing of infracyanine green using retinal pigment epithelium and glial cell cultures.

PURPOSE: To undertake safety testing of infracyanine green (IFCG) in a cell culture model. METHODS: Experiments were undertaken in a cell culture model used previously to perform safety testing of indocyanine green (ICG). Human retinal pigment epithelium (RPE) and Müller cells were exposed to IFCG for 5 minutes, over a range of concentrations up to 0.5%. Experiments were repeated, using double-staining with trypan blue. Cell viability was measured at days 1, 5, and 15 using a mitochondrial dehydrogenase assay and a fluorescent live-dead probe containing calcein and ethidium homodimer-1. Viability was measured after exposure to 0.5% IFCG and 5 minutes of illumination with a vitrectomy endolight powered by a xenon light source. RESULTS: RPE viability was not reduced over the range of concentrations and follow-up intervals. RPE cells exposed to IFCG and illumination had reduced viability relative to the negative control (cells exposed to saline), but not relative to those exposed to saline and illumination. Glial cells showed reduced viability at days 1 and 5, but not day 15. Illumination did not further reduce viability. CONCLUSIONS: IFCG has been advocated as a safer macular vital stain than ICG. These results suggest that it is less likely to produce phototoxicity, but despite being nearly iso-osmolar, IFCG also produces damage in cultured glial cells.

Cell Culture Techniques↗
PubMed2003

Golf-related ocular injuries.

PURPOSE: To examine patient outcomes from golf-related ocular injuries. METHODS: A retrospective case review was undertaken of subjects with golf-related ocular injuries treated at the Auckland and Waikato Hospitals during the 5-year period from 1997 to 2002. RESULTS: Of 11 injuries treated in the 5-year period, five of the subjects incurred globe rupture with two subjects requiring enucleation. Seven of the injuries were from golf balls and four injuries were from golf clubs. Six of the subjects had a final visual acuity of 6/48 or worse. CONCLUSION: Golfing injuries, though uncommon, are frequently associated with severe ocular trauma and poor visual outcome. Although unpredictable and difficult to avoid, proper golf etiquette and safety may diminish the incidence of golf-related ocular injures. Injuries caused by golf clubs occurred only in children.

Adolescent↗
PubMed2003

Further evidence for proinflammatory nature of perfluorohexyloctane in the eye.

BACKGROUND: The authors present a clinicopathological report of their initial experience with perfluorohexyloctane (F6H8), a novel semifluorinated liquid fluorocarbon developed as a long-term vitreous substitute. METHODS: A retrospective observational review was performed of five patients in whom F6H8 had been used for management of rhegmatogenous retinal detachment. Surgical specimens taken from two patients at the time of F6H8 removal were also submitted for histopathological, immunohistochemical and electron microscopic analysis. RESULTS: Clinical and histological analysis of the present small case series confirmed the propensity of F6H8 to emulsify, and suggested a probable biological reaction to F6H8. Surrounding and engulfing the F6H8 were numerous cells morphologically in keeping with macrophages. Immuno-histochemistry confirmed macrophage phenotype but electron microscopic evaluation showed epithelial ultra-structural features. It is suggested that the finding of macrophagic phenotype in cells with epithelial ultra-structure provides further evidence for a continuum of phenotypic differentiation of the pigment epithelial cells as part of the repair and regeneration that is the proliferative vitreo-retinopathy (PVR) response. CONCLUSIONS: The data do not indicate any benefit of F6H8 over other perfluorocarbons for use in short-term post-operative intraocular tamponade. Although early experience suggests that F6H8 use in primary vitrectomy with minimal PVR is acceptable and produces temporary inflammatory effects only, these cases can often be successfully managed by conventional scleral buckling techniques, or vitrectomy with standard tamponading agents, without the need for F6H8 and subsequent extra surgical procedures. Furthermore in eyes already predisposed to inflammation through prior surgery and/or presence of PVR, the inflammatory effects were not insignificant. The use of F6H8 is not recommended in the clinical setting, except as part of a controlled trial subject to the approval of an ethics committee and informed consent.

Adolescent↗