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Minas T Coroneo

Publications and source records attributed to Minas T Coroneo.

At least 19 recordsLinked to original sources
PubMed2007

The phenotype of limbal epithelial stem cells.

PURPOSE: The purpose of this study was to identify phenotypic markers of human limbal stem cells in fetal and adult corneas. METHODS: RNA from microscopically dissected superficial limbal and central fetal (18 weeks) corneas was amplified and used to generate P(32)-labeled, reverse-transcribed antisense RNA that was linearly amplified and hybridized to a focused stem cell cDNA microarray. Differential gene expression of fetal limbus was compared with the expression of central cornea. Microarray differential expression experiments were performed on P63-expressing primary cultured limbal epithelial cells (passage 1; Pa1) and primary cells passaged 5 times (Pa5). Semiquantitative RT-PCR assay and immunohistochemistry were performed on fetal and adult corneas and cultured primary limbal epithelial cells, to confirm the results of the microarray experiments. Slow-cycling (pulsed bromodeoxyuridine label-retaining) limbal epithelium in corneal organ culture was studied for the expression of four selected upregulated limbal genes. RESULTS: Of the 266 genes tested, 33 were differentially overexpressed (more than twofold) in the fetal limbus (compared with central cornea) and primary cultured limbal epithelium compared with primary cells after 5 passages. Cytokeratin 15 (CK15) and cytokeratin 14 (CK14) are expressed in limbal basal epithelium and P-cadherin (CDH3) and Wnt-4 expression was restricted to basal and immediate parabasal limbal epithelium of both the adult and fetal corneas). Bromodeoxyuridine label retaining epithelium in corneal organ culture (slow-cycling cells) expressed the four selected limbal upregulated genes. CONCLUSIONS: For the first time, a focused stem cell pathway microarray analysis has been performed on fetal cornea and cultured limbal explant epithelium. CK15, CK14, CDH3, and Wnt-4 are expressed in the basal limbal epithelial cells.

Adult↗
PubMed2006

Ultraviolet fluorescence photography: patterns in established pterygia.

PURPOSE: To investigate established pterygia using our newly developed ultraviolet fluorescence photography (UVFP) system. DESIGN: Prospective observational case series. METHODS: setting: Prince of Wales Hospital, Sydney, Australia. study population: Fourteen patients (both eyes) attending the Ophthalmology Clinic at Prince of Wales Hospital for assessment of their established pterygia. There were eight men and six women, with an age range of 26 to 62 years. A total of 15 (75%) of 20 had primary pterygia, and five (25%) of 20 had recurrent pterygia. There were no specific exclusion criteria. observation procedures: Ultraviolet and standard (control) photographs were taken of the nasal and temporal interpalpebral regions bilaterally. main outcome measures: The presence of established pterygia detected by standard photography and the corresponding presence and patterns of areas of fluorescence detected by UVFP. RESULTS: In the 14 patients, 20 established pterygia were identified on standard photography. On UVFP, four patterns of fluorescence of established pterygia were identified. Of the 20 pterygia, six (30%) of 20 demonstrated fluorescence at the leading edge of the pterygium, seven (35%) of 20 demonstrated fluorescence at the limbus, three (15%) of 20 demonstrated fluorescence at both the leading edge and the limbus, and four (20%) of 20 demonstrated no visible fluorescence. CONCLUSIONS: In this study, we describe patterns of fluorescence in established pterygia by UVFP. We hypothesize that the areas of fluorescence represent areas of cellular activity within the pterygium. The patterns of fluorescence may be useful to further understand of pterygium growth and pathogenesis.

Adult↗
PubMed2006

Cultured human ocular surface epithelium on therapeutic contact lenses.

BACKGROUND: This study was initiated after observation of some intriguing epithelial growth properties of contact lenses used as a bandage for patients after pterygium surgery. AIM: To determine the efficacy of culturing human ocular surface epithelial cells on therapeutic contact lenses in autologous serum with a view of using this system to transfer epithelial cells to patients with persistent corneal or limbal defects. METHODS: Excess graft tissue resected from patients undergoing pterygium surgery (n = 3) consisting of limbal epithelium was placed on siloxane-hydrogel contact lenses (lotrafilcon A and balafilcon A). Limbal explants were cultured in media with 10% autologous serum. Morphology, proliferative capacity and cytokeratin profile were determined by phase contrast, light and electron microscopy, and immunohistochemical analysis. RESULTS: Lotrafilcon A contact lenses sustained proliferation and migration from limbal tissue. Cells became confluent after 10-14 days and consisted of 2-3 layers with a corneal phenotype (CK3(+)/CK12(+)/CK19(-)) and a propensity to proliferate (p63(+)). Electron microscopy showed microvilli on the apical surface with adhesive projections, indicating that these cells were stable and likely to survive for a long term. Growth was not observed from limbal explants cultured on balafilcon A contact lenses. CONCLUSION: A method for culturing human ocular surface epithelium on contact lenses that may facilitate expansion and transfer of autologous limbal epithelial cells while avoiding the risks associated with transplanting allogeneic tissue has been developed. This technique may be potentially useful for the treatment of patients with limbal stem cell deficiency.

Bandages↗
PubMed2006

Retinal ganglion cell line apoptosis induced by hydrostatic pressure.

Cellular responses to changes in pressure are implicated in numerous disease processes. In glaucoma apoptosis of retinal ganglion cells (RGCs) is associated with elevated intra-ocular pressure, however, the exact cellular mechanisms remain unclear. We have previously shown that pressure can induce apoptosis in B35 and PC12 neuronal cell lines, using an in vitro model for pressure elevation. A novel RGC line allows us to study the effects of pressure on retinal neurons. 'RGC-5' cultures were subjected to elevated ambient hydrostatic pressure conditions in our model. Experimental pressure conditions were 100 mm Hg and 30 mm Hg, representing acute (high) and chronic (lower-pressure) glaucoma, and 15 mm Hg for normal intra-ocular pressure, set above atmospheric pressure for 2 h. Negative controls were treated identically except for the application of pressure, while positive controls were generated by treatment with a known apoptotic stimulus. Apoptosis was determined by a combination of cell morphology and specific TUNEL and Annexin V fluorescent markers. These were assessed simultaneously by laser scanning cytometry (LSC), which also enabled quantitative marker analysis. RGC-5 neurons showed a significantly increased proportion of apoptotic cells compared with controls; maximal at 100 mm Hg, moderate at 30 mm Hg and not statistically significant at 15 mm Hg. This graded response, proportionate to the level of pressure elevation, is representative of the severity of analogous clinical settings (acute, chronic glaucoma and normal). These results complement earlier findings of pressure-induced apoptosis in other neuronal cultures. They suggest the possibility of novel mechanisms of pressure-related mechanotransduction and cell death, relevant to the pathogenesis of diseases such as glaucoma.

Animals↗
PubMed2006

Ultraviolet fluorescence photography to detect early sun damage in the eyes of school-aged children.

PURPOSE: To develop a method to detect precursors of ocular sun damage using ultraviolet fluorescence photography (UVFP). DESIGN: Observational cross-sectional study METHODS: settings: Preschool, primary, and high school in Sydney, Australia. study population: 71 children ages 3 to 15 years old (both eyes). Inclusion criteria were children attending the schools who gave consent. There were no exclusion criteria. observation procedures: UV and standard (control) photographs were taken of the nasal and temporal interpalpebral regions bilaterally. main outcome measures: Presence of areas of increased fluorescence detected by UVFP, or presence of pinguecula detected by standard photography. RESULTS: Established pingueculae, on standard photography, were seen in seven of 71 (10%) children; all were 13 years of age or older. On UVFP, all of these pingueculae demonstrated fluorescence. In total, 23 of 71 (32%) had increased fluorescence detected on UVFP, including the seven of 23 (30%) with pingueculae. Of the remaining 16 of 23 (70%), the changes were only detectable using UVFP. Fluorescence on UVFP was seen in children ages 9 years and above, with prevalence increasing with age. The presence of fluorescence (in at least one region) was 0 of 15 (0%) for children ages 3 to 5 years, 0 of 12 (0%) of children ages 6 to 8 years, 6 of 23 (26%) for those ages 9 to 11 years, and 17 of 21 (81%) of those ages 12 to 15 years. CONCLUSIONS: We hypothesize that the areas seen to fluoresce on UVFP but not detectable on control photography represent precursors for ophthalmohelioses. Our preliminary data strongly suggests that UVFP is a sensitive method for detecting early ocular sun damage occurring many years before clinical manifestations.

Adolescent↗
PubMed2006

Ocular effects of cosmetic products and procedures.

Cosmetic products and procedures can produce adverse effects on the ocular surface, ranging from mild discomfort to vision-threatening conditions. Complications of skin and eye products can be related to allergy or toxicity, often attributable to perfumes. Complications of blepharoplasty may be associated with overcorrection, scarring, or uneven contour of the lid margins, conditions that can cause significant ocular surface disease until they are corrected. Ocular surface effects of botulinum toxin injection include dry eye syndromes and also epiphora. More serious complications occur (rarely) and are dose- and location-related. Adverse effects of micropigmentation procedures involve pathological processes or, simply, poor cosmetic results. In certain youth cultures, special-effect contact lenses and even decorative conjunctival implants have gained popularity, presenting a wide variety of dangers, often attributable to poor education about care and hygiene.

Cosmetic Techniques↗
PubMed2006

Spontaneous resolution of corneal oedema following Descemet's detachment.

We report a case of spontaneous resolution of corneal oedema in the presence of a large persistent Descemet's detachment in a 71-year-old woman. Detachment of Descemet's membrane occurred during phacoemulsification surgery and produced significant corneal oedema. The patient declined surgical repair. Six months later the corneal oedema resolved and in vivo confocal microscopy showed endothelial cells on the posterior stroma in the region of the detachment. Endothelial cell hypertrophy, migration and redistribution were thought to be responsible for reversal of the corneal oedema. Experimental evidence and clinical studies raise the possibility that limited endothelial cell proliferation may occur.

Aged↗
PubMed2006

UVB-mediated induction of cytokines and growth factors in pterygium epithelial cells involves cell surface receptors and intracellular signaling.

PURPOSE: Pterygium is a proliferative, inflammatory, and invasive ocular surface disease associated with excessive ultraviolet (UV) exposure. This investigation was conducted to identify UV activated signaling pathways in pterygium epithelial cells (PECs) that mediate cytokine and growth factor production and to determine whether these pathways are sensitive to blockade by anti-inflammatory agents such as retinoic acid (RA) and interferon (IFN)-alpha. METHODS: PECs were pretreated with or without inhibitors of the ERK1/2, JNK, and p38 (PD98059, SB202190, and SB203580, respectively) mitogen-activated protein kinases (MAPK) or with inhibitors of the tyrosine kinase activity of epidermal growth factor receptor (EGFR; PD153035) and platelet-derived growth factor (PDGF; AG1295); exposed to UVB (20 mJ/cm2); and then further treated with the same inhibitors. Media were harvested and analyzed by ELISA for interleukin (IL)-6, IL-8, and vascular endothelial growth factor (VEGF). Cytokine mRNA was assessed by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Inhibitors of ERK1/2, JNK, and p38 MAPKs significantly abolished the UVB-mediated increase in IL-6, IL-8, and VEGF. PD153035 reduced IL-8, AG1295 repressed IL-6, and both inhibitors partially downregulated VEGF production in UV-exposed PECs. RA and IFN-alpha dose dependently abrogated IL-6 and IL-8 but had no effect on VEGF expression after UV exposure. CONCLUSIONS: The results have identified a stress-induced intracellular pathway and potential cell-surface transmitters that may be relevant to pterygium development. Moreover, two anti-inflammatory/antiangiogenic agents were identified that reduced cytokine production in the study model. Topical application of these drugs may benefit patients with pterygia, potentially reducing the necessity for surgical intervention.

Cells, Cultured↗
PubMed2005

Spectrum of clear corneal incision cataract wound infection.

PURPOSE: To describe the presentation, management, and outcome of 5 patients who presented with main-port or side-port wound infection after uneventful clear corneal cataract surgery. SETTING: Ophthalmic Surgery Centre, Chatswood, and Department of Ophthalmology, Prince of Wales Hospital, Randwick, Australia, and Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. METHODS: This retrospective case series comprised 5 patients who had uneventful clear corneal phacoemulsification surgery and developed either a main-port or side-port wound infection. The clinical features, microbiologic studies, management, and results are reported. RESULTS: The median age of the patients was 79 years. Infection of the main-port incision occurred in 3 cases and of the side port in 2 cases. The patients presented from a few days to several weeks after uneventful phacoemulsification. In 2 cases, the bacteria Pseudomonas aeruginosa and Staphylococcus aureus were isolated. In 1 case, the fungus Aspergillus was isolated and required extensive medical and surgical treatment. In the other 2 cases; empiric antimicrobial therapy was given because no organism was isolated in 1 case, and in the other milder case, microbiological investigations were not performed. Final visual acuity was 6/4 in 2 cases and 6/5, 6/12, and 6/18 in 1 case each. CONCLUSIONS: Bacterial or fungal wound infection can present within days or even several weeks following clear corneal cataract surgery. Patients with ocular discomfort or blurred vision after such surgery should be advised to report promptly. Rapid identification and appropriate management of patients with clear corneal wound infection can result in good visual outcomes.

Aged↗
PubMed2005

Evaluation of extraocular electrodes for a retinal prosthesis using evoked potentials in cat visual cortex.

OBJECTIVE: To assess the efficacy of a device using extraocular electrodes as a retinal prosthesis by evaluating the responses evoked in the visual cortex to electrical stimulation. METHODS: In anaesthetised cats, a lateral orbital dissection and ipsilateral parietal craniotomy was performed. Two extraocular retinal prosthesis (ERP) disc electrodes were sutured to the sclera on the lateral and superior aspects of the globe. Retinal stimulation was performed with charge-balanced constant-current pulses. Potentials evoked in the visual cortex were measured with a ball electrode placed on the lateral gyrus after removal of the dura. RESULTS: Stable attachment of the ERP electrodes to the globe was achieved with scleral sutures. Visual cortex responses were recorded with the electrodes in bipolar and monopolar configurations. The evoked response consisted of an early component with a peak around 8 ms, and a late component with a peak after 50 ms. Thresholds for evoking a response occurred at current intensities as low as 500 microA. Through extrapolation from evoked response amplitude data, thresholds as low as 300 microA were calculated. Cathodal monopolar stimulation demonstrated lower thresholds than anodal stimulation for evoking cortical responses. CONCLUSIONS: The ERP electrodes can be easily attached to the globe and are effective in electrically stimulating the retina, evoking responses in the primary visual cortex. Threshold charge-density was within safe limits for neural stimulation.

Animals↗
PubMed2005

Feasibility of extraocular stimulation for a retinal prosthesis.

BACKGROUND: We present a new approach to developing a retinal prosthesis for blind patients based on extraocular stimulation of the eye with disc electrodes. METHODS: Experiments to assess the feasibility of using extraocular stimulation in a retinal prosthesis were carried out in anaesthetised adult cats (n=6). A craniotomy and lateral orbital dissection were performed. Ball or disc electrodes were placed on the posterior scleral surface of the eye after incision of the periorbita. Cortical potentials evoked by electrical stimulation with these electrodes were recorded at the primary visual cortex. The viability of adapting the Nucleus 24 auditory brainstem implant (ABI) as an extraocular retinal prosthesis was also investigated. RESULTS: Electrodes placed on the exterior of the eye could reliably evoke visual cortex responses for a variety of configurations. Threshold currents for eliciting an evoked response were lower than 100 microA with single pulses. Strength-duration curves and cortical activation maps were obtained for different stimulus paradigms. It was possible to excite the retina to evoke a cortical response using the electrodes and stimulus capabilities in a standard Nucleus 24 ABI. INTERPRETATION: It is possible to electrically stimulate the retina with electrodes placed in an extraocular location. Threshold currents required to elicit a response were low, and comparable to epiretinal implants. Prototype electrodes, and a potential implant, were found to be effective at retinal stimulation.

Animals↗
PubMed2005

Stretch-activated channels: a mini-review. Are stretch-activated channels an ocular barometer?

All cells are subject to physical forces by virtue of their position in a dynamically changing environment. This review outlines the various putative 'mechanosensors', or sensors of pressure cells possess, and discusses in particular the role stretch-activated membrane channels play in pressure recognition and transduction. The widespread occurrence of these channels is discussed and these 'mechanosensors' are related to pressure-related diseases, in particular, glaucoma.

Eye Diseases↗
PubMed2005

Centripetal lens epithelial cell migration: a prospective study of the Alcon SA60AT intraocular lens.

PURPOSE: To evaluate prospectively the incidence and severity of centripetal lens epithelial cell migration (CLECM) onto the anterior surface of the Alcon SA60AT intraocular lens (IOL). METHODS: One hundred and four consecutive cases of SA60AT IOL implantations were prospectively evaluated. At the 1-month postoperative visit, best corrected visual acuity (BCVA) was obtained. Following maximal pupillary dilatation, the extent of CLECM was assessed using a simplified grading scale (0-4). The centrality of the lens within the capsular bag was recorded. Patients with the highest grade of CLECM were recalled for reassessment at a minimum of 3 months. RESULTS: Centripetal lens epithelial cell migration data were obtained on 99 patients. Of these, 94% demonstrated CLECM of varying severity at 1 month postoperatively. The severity was low grade in 54% of patients (29% grade 1, 24% grade 2), and high grade in 40% of patients (16% grade 3, 24% grade 4). BCVA results were good (91.9% 6/6 or better) and did not correlate with CLECM grade. Operative capsulorhexis size did not correlate with the severity of CLECM. The lens was well-centred in 91 of 92 patients in whom lens position was assessed. Twenty-three patients with grade 4 CLECM at 1 month were brought back for reassessment (3.5-13 months postoperatively) and 18 of these demonstrated complete regression of CLECM (to grade 0). CONCLUSIONS: There is a high incidence and severity of CLECM 1 month postoperatively using the Alcon SA60AT IOL. There was no significant correlation between CLECM grade and either BCVA at 1 month, capsulorhexis size or lens centration. CLECM appears to be a frequent, benign and transient event with this lens.

Acrylic Resins↗
PubMed2005

Stimulation of the retina with a multielectrode extraocular visual prosthesis.

BACKGROUND: An extraocular approach to developing a retinal prosthesis for blind patients using electrodes placed on the outer surface of the eye is suggested. Experiments were carried out to determine the feasibility of this approach, and evaluate electrode configurations and parameters for stimulation. METHODS: In anaesthetized cats, a 21-electrode extraocular retinal prosthesis (ERP) array was sutured to the sclera over the lateral surface of the eye. Electrically evoked potentials (EEP) were recorded at the visual cortex bilaterally in response to retinal stimulation with the electrode array. Bipolar stimulation of the ERP array electrodes in horizontal and vertical configurations and at different interelectrode separations was investigated with biphasic constant-current pulses. RESULTS: Electrical stimulation of the lateral retina with an ERP elicited EEP that were higher in the ipsilateral visual cortex. The threshold for bipolar retinal stimulation was 500 microA. EEP amplitude increased with increases in stimulus pulse duration and current intensity. Retinal stimulation was slightly more effective with electrodes in a vertical as opposed to horizontal orientation. A larger interelectrode separation resulted in a higher EEP amplitude. CONCLUSIONS: Retinal stimulation with a prototype ERP array is demonstrated. The thresholds for retinal excitation are below safe charge-density limits for chronic neural stimulation. Ipsilateral localization of the EEP suggests that localized retinal stimulation is occurring. An ERP is a new approach to retinal prosthesis research, and might lead to the development of a low-resolution visual prosthesis for blind patients.

Animals↗