PubMed Health⌕ Search

Biomedical subjects

Peng T Khaw

Publications and source records attributed to Peng T Khaw.

At least 19 recordsLinked to original sources
PubMed2003

Optic disc hemorrhage in Asian glaucoma patients.

PURPOSE: To assess the prevalence of optic disc hemorrhage in Asian patients with established glaucoma using a recently described, highly sensitive detection method. MATERIALS AND METHODS: Patients entering a trial of glaucoma filtering surgery in Southeast Asia (The Singapore 5FU Study) were assessed for the presence or absence of optic disc hemorrhage using stereo flicker chronoscopy of stereophotograph pairs. RESULTS: A total of 167 patients (117 males and 50 females) were assessed, of whom 128 were Chinese. Primary open-angle glaucoma was diagnosed in 90 patients, primary angle-closure glaucoma in 69 patients, and pseudoexfoliative or pigment dispersion glaucoma in 7 patients. Five eyes of 5 patients had disc hemorrhage at enrollment (5/167), a rate of 2.99%. Four patients with disc hemorrhage had primary open-angle glaucoma and 1 had primary angle-closure glaucoma. There were no significant differences in global visual field indices, AGIS scores, or intraocular pressures between eyes with and without disc hemorrhage. All disc hemorrhages were seen in eyes prior to trabeculectomy. CONCLUSIONS: The prevalence of disc hemorrhage in the current study was comparable to that seen in primary open-angle glaucoma in clinic-based studies of white patients, but far less than that reported in normal-tension glaucoma studies. Hemorrhages were more common in primary open-angle glaucoma than primary angle-closure glaucoma.

Ethnicity↗
PubMed2003

Matrix metalloproteinase inhibition modulates postoperative scarring after experimental glaucoma filtration surgery.

PURPOSE: To determine whether postoperative application of a broad-spectrum matrix metalloproteinase (MMP) inhibitor, GM6001 (ilomastat), reduces scarring after glaucoma filtration surgery. METHODS: In a randomized, prospective, masked-observer study, 40 New Zealand White rabbits underwent modified glaucoma filtration surgery. The animals were randomly allocated to receive postoperative subconjunctival injections of either phosphate-buffered saline (PBS) or 100 microM ilomastat for 10 days. The animals were killed on days 7, 14, 21, and 30. Clinical characteristics, which included bleb morphology and intraocular pressure, were recorded. Tissue sections were immunohistochemically stained for alpha smooth muscle actin (alphaSMA) and extracellular matrix components in the two groups. RESULTS: Surgical outcome was significantly prolonged in the ilomastat-treated group compared with the vehicle-treated group (P < 0.001). At day 30, all the blebs had survived except two in the ilomastat-treated group, whereas no blebs survived to day 30 with vehicle treatment (n = 11). The intraocular pressure remained significantly lower throughout the course of the experiment in the ilomastat group compared with the vehicle group (P < 0.0017). Histologically, less scar tissue was observed at the sclerostomy site with inhibition of MMP, compared with vehicle treatment. CONCLUSIONS: The data presented suggest that the healing response after surgery can be modulated by inhibiting the effects of MMPs. Inhibition of MMP significantly improved surgical outcome by reducing the amount of scar tissue produced. By targeting the actions of these proteolytic enzymes, a more controlled and physiological method of modulating scarring may be achieved.

Actins↗
PubMed2003

Matrix metalloproteinase inhibition modulates fibroblast-mediated matrix contraction and collagen production in vitro.

PURPOSE: To investigate the effect of matrix metalloproteinase (MMP) inhibition on fibroblast-mediated matrix contraction and production. METHODS: Free-floating fibroblast-populated type I collagen lattices were prepared with human Tenon's capsule fibroblasts. Lattice areas were photographed and digitally analyzed to indicate the degree of lattice contraction. Quantitative competitive reverse transcription-polymerase chain reaction (QCRT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to quantify mRNA and protein respectively for MMP-1, -2, and -3 by fibroblasts during lattice contraction. Gelatin zymography demonstrated activity of MMPs released into the conditioned medium of contracting lattices. Concentrations of the broad-spectrum MMP inhibitors ilomastat, CellTech (Slough, UK), and BB-94 were added to the contracting fibroblast-populated collagen lattices. Secreted C-terminal propeptide of type I collagen was measured in conditioned medium of contracting lattices by ELISA. Fibroblast proliferation in the presence of concentrations of ilomastat was measured by using the reagent water-soluble tetrazolium-1 (WST-1). RESULTS: During contraction of type I collagen lattices, Tenon's capsule fibroblasts expressed MMP-1, -2, and -3 mRNA and protein. Zymography demonstrated the release of four gelatinolytic species into the conditioned medium of contracting lattices (57, 72, 91, and 100 kDa). Inclusion of MMP inhibitors in the zymogram-developing buffer reduced the proteolytic activity of the detected bands. MMP inhibition (1-100 microM) significantly reduced fibroblast-mediated collagen lattice contraction (P < 0.05), and this effect was found to be reversible. Ilomastat also significantly inhibited production of collagen in a dose-dependent manner (P < 0.05). No effect on fibroblast proliferation was found in the presence of ilomastat. CONCLUSIONS: MMPs are produced during Tenon's capsule fibroblast-mediated collagen lattice contraction. Broad-spectrum MMP inhibition significantly reduced matrix contraction and production without cell toxicity. Future clinical use of MMP inhibitors may be possible, because MMP inhibition significantly reduces fibroblast functions associated with contractile scarring.

Cell Division↗
PubMed2003

Human corneal epithelial cells require MMP-1 for HGF-mediated migration on collagen I.

PURPOSE: To investigate the potential regulation of matrix metalloproteinases (MMPs) by hepatocyte growth factor (HGF), and to identify individual MMPs essential for migration of human corneal epithelial cells. METHODS: Migration of human corneal epithelial cells (HCECs) was measured with a colony dispersion assay in response to concentrations of HGF (0-50 ng/mL). MMP activity in the conditioned media collected from the dispersion assay was assessed by zymography. The broad-spectrum MMP inhibitor ilomastat (1-100 microM) or an MMP-9-neutralizing antibody (1-10 microg/mL) were included in the dispersion assay to determine their effects on HCEC migration. Immunocytochemistry and in situ hybridization were used to localize MMP-1 in HCECs in the colony dispersion assay and in a human ex vivo corneal wound-healing model, respectively. ELISA for MMP-1 was performed on conditioned medium from migrating HCECs. Neutralizing antibodies to MMP-1 and -9 were added to an in vitro scratch-wound model to assess the effect on HCEC healing. RESULTS: HCEC migration (P < 0.05) and MMP-2 and -9 released into the medium increased in response to HGF in a dose-dependent manner up to 20 ng/mL. Broad-spectrum MMP inhibition significantly reduced HCEC migration (P < 0.05). In contrast, neutralization of MMP-9 increased migration (P < 0.05). MMP-1 was found in association with HCECs at the migratory leading edge in both the dispersion and the ex vivo wound-healing experiments, and was found to be stimulated above basal levels by HGF. Neutralization of MMP-1 significantly decreased (P < 0.05), whereas neutralization of MMP-9 significantly increased (P < 0.05), scratch-wound closure. CONCLUSIONS: This study provided novel data regarding HCEC migration in response to HGF and highlighted the importance of MMPs, particularly MMP-1 in migration and possibly reepithelialization in vivo. MMP-9 and/or -2 may be released by HCECs to remodel matrix behind the leading migratory front. Studies such as this are essential to assist in the safe and efficacious design of MMP inhibitors for therapeutic use in the eye.

Cell Movement↗
PubMed2003

Novel anterior segment phenotypes resulting from forkhead gene alterations: evidence for cross-species conservation of function.

PURPOSE: Mutations in murine and human versions of an ancestrally related gene usually result in similar phenotypes. However, interspecies differences exist, and in the case of two forkhead transcription factor genes (FOXC1 and FOXC2), these differences include corneal or anterior segment phenotypes, respectively. This study was undertaken to determine whether such discrepancies provide an opportunity for identifying novel human-murine ocular phenotypes. METHODS: Four pedigrees with early-onset glaucoma phenotypes secondary to segmental chromosomal duplications or deletions encompassing FOXC1 and 18 individuals from 9 FOXC2 mutation pedigrees underwent detailed ocular phenotyping. Subsequently, mice with mutations in Foxc1 or a related forkhead gene, Foxe3, were assessed for features of the human phenotypes. RESULTS: A significant increase in central corneal thickness was present in affected individuals from the segmental duplication pedigrees compared with their unaffected relatives (mean increase 13%, maximum 35%, P < 0.05). Alterations in corneal thickness were present in mice heterozygous and homozygous for Foxe3 mutations but neither in Foxc1 heterozygotes nor the small human segmental deletion pedigree. Mutations in FOXC2 resulted in ocular anterior segment anomalies. These were more severe and prevalent with mutations involving the forkhead domain. CONCLUSIONS: Normal corneal development is dependent on the precise dose and levels of activity of certain forkhead transcription factors. The altered corneal thickness attributable to increased forkhead gene dosage is particularly important, because it may affect the clinical management of certain glaucoma subtypes and lead to excessive treatment. The FOXC1 and Foxe3 data, taken together with the novel ocular phenotypes of FOXC2 mutations, highlight the remarkable cross-species conservation of function among forkhead genes.

Animals↗
PubMed2003

Evaluation of anti-TGF-beta2 antibody as a new postoperative anti-scarring agent in glaucoma surgery.

PURPOSE: Postoperative subconjunctival wound healing remains the commonest cause of late bleb failure after glaucoma filtration surgery. This study was undertaken to investigate whether the human monoclonal antibody that neutralizes transforming growth factor-beta2 (CAT-152; lerdelimumab) could be used as a postoperative agent to prevent scarring after glaucoma surgery and compared it with 5-fluorouracil (5-FU), to benchmark its potential clinical benefit. METHODS: In a randomized, controlled, masked-observer study, after modified glaucoma surgery, 48 rabbits were randomly allocated to receive a postoperative course of seven subconjunctival injections of CAT-152 (1 mg/mL), 5-FU (50 mg/mL), or no treatment. Bleb characteristics, the presence of subconjunctival drainage, and local reaction to treatment were assessed. Animals were killed on days 10, 21, and 30. Immunohistochemistry, histologic staining and electron microscopy were performed to demonstrate the mechanism of CAT-152-mediated effects on the extracellular matrix. RESULTS: CAT-152 significantly improved surgical outcome (log rank test, P < 0.001) and reduced subconjunctival collagen deposition (P < 0.01) compared with 5-FU and control. Median bleb survival was increased in the CAT-152 group (23.5 days) compared with the 5-FU (20 days) and control (16 days) treatment groups. CAT-152 treatment improved bleb morphology (P < 0.05) and was well tolerated. 5-FU prolonged the duration of corneal epitheliopathy (P < 0.01). CONCLUSIONS: Postoperative administration of CAT-152 significantly improved surgical outcome, reduced subconjunctival scarring, and minimized the risk of corneal side effects compared with the anti-scarring agent 5-FU. These findings suggest that CAT-152 may offer therapeutic benefit as a postoperative agent to prevent subconjunctival scarring after glaucoma filtration surgery.

Animals↗
PubMed2003

Determinants of intraocular pressure and its association with glaucomatous optic neuropathy in Chinese Singaporeans: the Tanjong Pagar Study.

PURPOSE: To examine the relationship between intraocular pressure (IOP), anthropomorphic, demographic, socioeconomic, systemic, and ocular factors and glaucomatous optic neuropathy (GON) in Chinese people. METHODS: Chinese people (n = 2000), aged 40 to 79 years, were selected from the Singapore electoral register. Of the 1717 considered eligible for examination, 1232 participated, representing a response rate of 71.8%. IOP was estimated with Goldmann applanation tonometry. The drainage angle was assessed with static and dynamic gonioscopy. The optic nerve was examined at high magnification through a dilated pupil with a fundus contact lens or a +78-D lens. Static automated visual field testing was performed on subjects with suspected glaucoma. GON was diagnosed on the basis of structural and functional abnormalities of the optic nerve. RESULTS: The main independent determinants of higher IOP were higher systolic blood pressure (P < 0.001), quadrants of any peripheral anterior synechiae (PAS, P = 0.02) and width of the drainage angle (P = 0.049). A 100- micro m increase in corneal thickness was associated with an increase in mean IOP of 1.5 to 1.8 mm Hg (P < 0.001). Odds of GON increased 1.2 times per 1-mm Hg increase in screening IOP. A clear association between corneal thickness and GON was not identified. CONCLUSIONS: Clinical IOP estimates are related to systolic blood pressure and corneal thickness. Variation in IOP with angle width may suggest that trabecular compaction significantly contributes to causes of the increase in IOP, independent of angle-closure. GON is an IOP-related phenomenon among Chinese Singaporeans.

Adult↗
PubMed2002

The severity and spatial distribution of visual field defects in primary glaucoma: a comparison of primary open-angle glaucoma and primary angle-closure glaucoma.

OBJECTIVE: To compare the characteristics of visual field defects in primary angle-closure glaucoma (PACG) and primary open-angle glaucoma (POAG). METHODS: Subjects with primary glaucoma aged 30 years and older were prospectively considered for inclusion. Automated static white-on-white perimetry was performed. A minimum of 2 reliable tests was required with a mean deviation (MD) within 2 dB on 2 tests. Subjects with previous symptomatic angle-closure, normal-tension glaucoma, visually significant cataract, or previous intraocular surgery were excluded. RESULTS: Of 234 subjects assessed, 129 had POAG, and 105 had PACG. The MDs (POAG group, -13.3 dB; PACG group, -18.0 dB) indicated more severe visual loss in subjects with PACG. In subjects with POAG, the superior hemifield was more severely affected than the inferior. This was less pronounced in subjects with PACG. Following stratification by MD, the difference between hemifields was marked in the mild (-10 dB<or=MD) and moderate (-20 dB<or=MD<-10 dB) subgroups but was not present in the severe (MD<-20 dB) subgroup. We detected differences between POAG and PACG in retinal sensitivity between the superior and inferior hemifields, independent of severity of damage. CONCLUSIONS: The pattern of visual field loss was different in the 2 diseases. This may give insight into the pattern of visual loss in predominantly pressure-dependent glaucomatous optic neuropathy.

Aged↗
PubMed2002

Differential expression of matrix metalloproteinases 2 and 9 by glial Müller cells: response to soluble and extracellular matrix-bound tumor necrosis factor-alpha.

Glial Müller cells are known to undergo functional and morphological changes during retinal proliferative disorders, but very little is known of the contribution of these cells to extracellular matrix deposition during retinal wound healing and gliosis. This study constitutes the first demonstration that retinal Müller cells express two major matrix metalloproteinases (MMPs), gelatinase A (MMP-2) and gelatinase B (MMP-9), implicated in cell migration and matrix degradation. Although mRNA and gelatinolytic activity of MMP-2 remained unchanged in cultured Müller cells, basal levels of MMP-9 mRNA observed after subculture at 24 hours, markedly declined after 48 or 72 hours. This correlated with the expression of MMP-9 gelatinolytic activity that peaked at 24 hours, but gradually decreased at 48 and 72 hours. Tumor necrosis factor-alpha, in both a soluble form or bound to collagen and fibronectin, increased MMP-9 mRNA and gelatinolytic activity, but not MMP-2 expression, and its effect could be blocked by anti-tumor necrosis factor-alpha antibodies. The results suggest that Müller cells may aid in the local control of extracellular matrix deposition during retinal proliferative disorders, and that interaction of these cells with matrix-bound cytokine may influence their pathological behavior. Control of Müller cell production of MMP-9 may constitute an important target for the design of new therapeutic approaches to treat and prevent retinal proliferative disease.

Adult↗
PubMed2002

Diode laser cyclophotocoagulation: role in the management of refractory pediatric glaucomas.

PURPOSE: To report the efficacy and complications of diode laser cyclophotocoagulation (cyclodiode) in the management of refractory pediatric glaucomas. DESIGN: Noncomparative interventional case series. PARTICIPANTS: Pediatric patients with uncontrolled glaucoma. Seventy-seven eyes of 61 patients underwent cyclodiode. Mean age was 7.4 years (range, 0.4-17 years). MAIN OUTCOME MEASURES: Intraocular pressure (IOP), visual acuity, complications. RESULTS: Diagnoses included aphakic glaucoma, congenital glaucoma, juvenile chronic arthritis, aniridia, anterior segment dysgenesis, and Sturge-Weber syndrome. Sixty percent of eyes were aphakic, and 64% had undergone at least one previous surgical procedure for glaucoma. Patients underwent a mean of 2.3 treatment sessions per eye (maximum, 8 sessions). Mean pretreatment IOP was 32.0 mmHg. After one treatment session, 62% had a clinically useful reduction in IOP (<22 mmHg or by 30%), but this had fallen to 37% by 12 months. With repeat cyclodiode, 72% had a clinically useful reduction in IOP for a year or more (mean, 8.4-month interval between treatments). Aphakic eyes had a more sustained IOP reduction (P < 0.01 log rank test). Of treatment failures, 13% had no useful IOP response, and three eyes developed subsequent retinal detachment and loss of vision. No other eyes lost vision because of cyclodiode-related complications. In 5.5% of the treatment sessions there was a significant posttreatment inflammatory episode. Cyclodiode treatment did not enable a reduction in the number of medications. CONCLUSIONS: With repeated treatment, cyclodiode can provide effective control of IOP. However, the success rate is lower than with adults, and younger eyes may recover from treatment more rapidly. Although response may be temporary, cyclodiode has a lower rate of severe adverse effects than surgical modalities and has roles as a temporizing measure, as an adjunct to surgery, or in managing selected patients in whom surgery is undesirable because of a high risk of surgical complications.

Adolescent↗
PubMed2002

Human antitransforming growth factor beta(2) monoclonal antibody--a new modulator of wound healing in trabeculectomy: a randomized placebo controlled clinical study.

PURPOSE: The human monoclonal antibody that neutralizes the growth factor TGFbeta(2) (CAT-152) safely and effectively inhibits in vitro and in vivo models of conjunctival scarring. This phase I/IIa clinical trial was designed to assess the safety and tolerability of CAT-152 in patients undergoing trabeculectomy. DESIGN: Prospective randomized placebo-controlled clinical trial. PARTICIPANTS AND CONTROLS: Twenty-four patients who were due to undergo primary trabeculectomy at Moorfields or Western Eye Hospitals in London, England, were recruited for this study and randomly assigned to treatment with either CAT-152 (100 microg in 100 microl) (n = 16) or placebo (n = 8). METHODS: The treatment regimen was a series of four 100-microl subconjunctival injections, given immediately before and after surgery, and at 1 day and 1 week postoperatively. Assessment consisted of a full ophthalmic examination with recordings of the logarithm of the minimum angle of resolution visual acuities performed at baseline and at set intervals after surgery. Any adverse events were recorded. MAIN OUTCOME MEASURES: Logarithm of the minimum angle of resolution visual acuity, intraocular pressure, complications, and adverse events. RESULTS: The results of 12 month's follow-up on all patients are documented. There were no statistically significant differences in the incidence of complications between the two groups, and no serious adverse events related to the study drug occurred. Blebs after CAT-152 antibody treatment were diffuse, noncystic, and nonavascular, unlike blebs associated with antimetabolites. The fall in intraocular pressure was greater in the CAT-152 group at 3 and 6 months (P < 0.05) and approached statistical significance at 12 months. There was a trend toward less intervention in those patients treated with CAT-152. The small number of patients included limited the power of the study (34%) to detect a difference between groups. Sixteen patients in each arm of the study would be required to obtain a power of 90% with a 5% significance level. CONCLUSIONS: This is the first clinical study of CAT-152 in patients undergoing glaucoma filtration surgery. CAT-152 seems to be well tolerated, and based on these results further multicenter trials are underway.

Aged↗
PubMed2002

The corneal thickness and intraocular pressure story: where are we now?

A review of the current literature was conducted regarding the effect of corneal thickness on the diagnosis of glaucoma, and the influence of excimer laser refractive surgery on intraocular pressure (IOP) measurement with Goldmann applanation tonometry. In general, normals and primary open angle glaucoma patients have a similar distribution of corneal thickness; however, there is a wide variation, ranging from 427 to 716 micro m. Normal tension glaucoma patients have a tendency towards thinner corneas than normals; however, there is an overlap of thickness measurements of more than two-thirds in 95% of patients. There is a trend for ocular hypertensives to have thicker corneas than normals, but again there is an overlap of about one-third in 95% of patients. The general trend after excimer laser refractive surgery is for a decrease in IOP, with a mean fall in IOP measured of 0.63 mmHg per dioptre correction. There is, however, a large scatter of values with some patients having the same or lower IOP post-laser, but with other patients measuring higher pressures. Corneal thickness can influence IOP measurement by Goldmann applanation tonometry; however, the magnitude of the effect is subject to much individual variation.

Cornea↗
PubMed2002

Aniridia.

Explore the source record for details and available documents.

Aniridia↗
PubMed2002

Needle perforations of Molteno tubes.

PURPOSE: To investigate the effects of needle perforation of proximal Molteno tubes on intraluminal pressure in a constant flow system. MATERIALS AND METHODS: Balanced salt solution was infused at a rate of 2 microL/min through nonexpansile silicon tubing attached to a manometric reservoir, pressure transducer, and an occluded proximal Molteno glaucoma drainage device tube. As the intraluminal pressure rose to approximately 30 mm Hg, the tube was perforated once with needles ranging in size from 23G to 29.5 G (disposable insulin syringe). Intraluminal pressure was measured continuously throughout each test run for an average of 71 minutes each. RESULTS: The average stable intraluminal pressure ranged from 25 mm Hg for 29.5-G perforation to 15 mm Hg for 23-G perforation. The lowest single pressure recorded ranged from 3 mm Hg for 23-G perforations to 17 mm Hg for 29.5-G perforations. Pressures of less than 15 mm Hg were recorded in more than 60% of the 23-G and 25-G perforations, less than 20% of the 27-G perforations, and none of the 29.5-G perforations. CONCLUSION: At a flow rate of 2 microL/min of balanced salt solution, 23-G and 25-G needle perforations of silicone glaucoma drainage device tubes produce intraluminal pressures in vitro, which may result in low intraocular pressures. Immediate postoperative hypotony risk can be reduced if a smaller needle perforation is used.

Molteno Implants↗
PubMed2002

Apoptosis gene expression and death receptor signaling in mitomycin-C-treated human tenon capsule fibroblasts.

PURPOSE: To examine the effect of mitomycin-C on the expression of apoptosis genes in human Tenon capsule fibroblasts and to evaluate whether death receptor signaling modulates mitomycin-C cytotoxicity. METHODS: Bcl-2, Bax, Bcl-x, Fas (CD95) and tumor necrosis factor (TNF) receptor expression was determined by flow cytometry in control and mitomycin-C-treated Tenon fibroblasts. Fibroblast death was quantified using a lactate dehydrogenase release assay. The effect of Fas and TNF-receptor signaling was evaluated using Fas-specific antibodies and soluble TNF-alpha. RESULTS: Tenon fibroblasts constitutively express Bcl-2, Bax, and Bcl-x in culture. Mitomycin-C (0.4 mg/mL) induced a small but consistent increase in the expression of all three proteins. Tenon fibroblasts express low levels of Fas but are resistant to the effects of Fas-receptor ligation. Mitomycin-C (0.01-1.0 mg/mL) led to a significant increase in Fas expression at all concentrations tested (P < 0.01). Pretreatment with mitomycin-C (0.4 mg/mL) rendered fibroblasts susceptible to agonistic anti-Fas monoclonal IgM antibodies (50-500 ng/mL) and led to a further 50% reduction in viable fibroblasts at 48 hours, compared with mitomycin-C alone (P < 0.05). Antibodies that block the Fas receptor did not inhibit mitomycin-C-induced apoptosis. CONCLUSIONS: Mitomycin-C alters apoptosis gene expression and primes fibroblasts to the effects of Fas receptor ligation. Factors other than the level of Fas receptor expression modulate the response to Fas receptor signaling. Determining the signals that regulate fibroblast apoptosis may help to refine therapeutic strategies for switching off the subconjunctival healing response and maintaining intraocular pressure control.

Antibiotics, Antineoplastic↗
PubMed2002

In vitro characterization of a spontaneously immortalized human Müller cell line (MIO-M1).

PURPOSE: To characterize a spontaneously immortalized human Müller cell line and to determine whether it retains the characteristics of primary isolated cells without undergoing differentiation in vitro. METHODS: An immortalized cell line obtained from human retina was investigated for the expression of known markers of Müller cells, including cellular retinaldehyde binding protein (CRALBP), glutamine synthetase, epidermal growth factor receptor (EGF-R), alpha-smooth muscle actin (alpha-SMA), and glial fibrillary acidic protein (GFAP). Also examined were the morphologic features of these cells, by scanning and transmission electron microscopy, and their functional characteristics, by electrogenic responses to glutamate. In addition, comparative studies were made of these cells with primary cultures of freshly isolated human Müller cells. RESULTS: The cells expressed CRALBP, EGF-R, glutamine synthetase, and alpha-SMA, as judged by confocal microscopy and Western blot analysis of cell lysates. Western blot analysis did not detect GFAP in cell lysates, but confocal microscopy showed that occasional cells expressed GFAP after detachment from the monolayer. The morphologic features of the cells examined, as judged by scanning and transmission electron microscopy, resemble those of cells derived from primary cell cultures. They possess villous projections on their apical surfaces and contain loose bundles of microtubules aligned parallel to one another and the long axis of the cell process. Characteristically, they contain abundant deposits of glycogen particles that do not differ from those seen in primary isolated cells. Preliminary recordings with intracellular electrodes revealed that these cells have properties similar to those described for mammalian Müller cells and depolarize in response to L-glutamate without significant change in membrane resistance, consistent with the well-established electrogenic uptake of this amino acid. CONCLUSIONS: A spontaneously immortalized Müller cell line was characterized that retains the characteristics of primary isolated cells in culture. To the authors' knowledge, it constitutes the first human Müller cell line reported in the literature. It has been named MIO-M1 (Moorfields/Institute of Ophthalmology-Müller 1) after the authors' institution. Availability of this human cell line will facilitate studies designed to obtain a better understanding of the role of Müller cells in normal and pathologic conditions.

Actins↗
PubMed2002

Ocular developmental abnormalities and glaucoma associated with interstitial 6p25 duplications and deletions.

PURPOSE: Mutations in the forkhead transcription factor gene FOXC1 on 6p25 cause a range of ocular developmental abnormalities, with associated glaucoma. However, FOXC1 mutations have not been found in all similarly affected pedigrees mapping to this interval. This study was undertaken to investigate the potential role of 6p25 rearrangements in causing such phenotypes. METHODS: Two large families with autosomal dominant iris hypoplasia and early-onset glaucoma, 21 probands with Axenfeld-Rieger phenotypes not attributable to PITX2 mutations, and 7 individuals with documented 6p25 cytogenetic rearrangements, were investigated by genotyping and fluorescence in situ hybridization, with markers and probes from the 6p25 region. RESULTS: Interstitial 6p25 duplications were present in the unrelated families with iris hypoplasia, whereas an interstitial 6p25 deletion was identified in one Axenfeld-Rieger pedigree. Larger cytogenetic rearrangements, leading to trisomy or monosomy of the 6p25 region, resulted in microcornea and Rieger syndrome phenotypes, respectively. All the rearrangements encompassed FOXC1, increasing or decreasing the number of FOXC1 copies present, and appeared to correlate with the phenotypes observed. CONCLUSIONS: These findings represent the first example of both interstitial duplications and deletions cosegregating with a human developmental disorder that is attributable to altered dose of transcription factor. The data presented provide additional evidence for the pathogenicity of altered gene dosage of FOXC1 and suggest that a common mechanism is responsible for rearrangements of 6p25.

Base Sequence↗