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Biomedical subjects

Jonathan G Crowston

Publications and source records attributed to Jonathan G Crowston.

At least 19 recordsLinked to original sources
PubMed2007

Magnetic resonance imaging of the visual system in vivo: transsynaptic illumination of V1 and V2 visual cortex.

Brain nuclei directly receiving retinal projections are readily labeled in magnetic resonance images following intraocular injection of manganese (Mn). To assess whether Mn in retinal ganglion cell axons can be transsynaptically delivered to visual cortex, mice that had previously received intraocular Mn injection were anesthetized with isoflurane, and T1-weighted data sets were acquired of the eyes and brain using a 7-T magnetic resonance imaging machine. Image intensity within contralateral brain structures was evaluated by assessing 1) signal-to-noise ratios, 2) mean image intensity, and 3) mean image intensity normalized to facial muscle intensity. Image intensity was increased throughout the visual pathway including within contralateral visual cortex areas V1 and V2L. Mean normalized image intensity was greater by 53% in the ipsilateral optic nerve and by 31% and 28% in the contralateral lateral geniculate nucleus and superior colliculus, respectively (N=5, P<0.02, paired t test). In contralateral visual cortex areas V1 and V2L, image intensity was increased by 7.5% and 6.8%, respectively (P<0.02 for both, paired t test). Power analysis of the different evaluation methods yielded evidence of superior sensitivity using the normalization method. Reconstruction of the visual system based upon threshold analysis allowed simultaneous visualization of all portions of the major retinal projections to the brain. These results support use of high magnetic field MRI imaging and data normalization for in vivo quantitative analysis of the mouse brain visual system including visual cortex.

Animals↗
PubMed2006

Comparison of invasive and non-invasive tonometry in the mouse.

Assessment of the accuracy of non-invasive rebound tonometry, and comparison with invasive cannulation tonometry. An in vivo calibration technique was devised to improve the accuracy of the rebound tonometer. IOP was then measured in SW mice using both rebound and cannulation tonometry. The ability of the rebound tonometer to accurately measure small IOP reductions after instillation of a topical prostaglandin was also determined. With the rebound method, mid-afternoon IOP in two groups of similar aged SW mice was 15.9+/-3.9 mmHg (mean+/-s.d., n=25) compared to 16.3+/-1.2 mmHg (n=32) using the cannulation technique. This difference was not statistically significant (p=0.6). For serial measurements using both techniques in the same eyes of a third group of SW mice (n=14), mean IOP was 15.0+/-3.9 mmHg for rebound tonometry but only 13.4+/-2.3 mmHg for subsequent cannulation tonometry. This effect was subsequently shown to be a consequence of the rebound tonometry, as multiple rebound measurements induced a statistically significant reduction in IOP. The average IOP reduction observed 2 hr after a single application of topical latanoprost (200 ng) was 2.8+/-1.3 mmHg (p<0.001) and 2.4+/-4.7 mmHg (p=0.03) with cannulation and rebound tonometers, respectively. These differences were not significantly different (p=0.8). In vivo calibration of the rebound tonometer increased measurement accuracy and provided IOP values within the physiological range that agreed closely with the IOP measured by cannulation tonometry. However, IOP measurement with the rebound tonometer had larger variability compared with the cannulation method. Repeat IOP measurements with the rebound tonometer led to a reduction in IOP. The rebound tonometer was sufficiently sensitive to detect a 2-3 mmHg reduction in IOP following application of topical latanoprost. Despite these limitations, the rebound tonometer has a significant advantage over cannulation tonometry in that it permits longitudinal IOP measurement in conscious mice.

Administration, Topical↗
PubMed2006

Sustained effect of travoprost on diurnal and nocturnal intraocular pressure.

PURPOSE: To assess the diurnal and nocturnal persistency of intraocular pressure (IOP) reduction after omission of up to two doses of once-daily topical travoprost in patients with open-angle glaucoma or ocular hypertension. DESIGN: Prospective, open-label study. METHODS: Twenty subjects underwent three sessions of 24-hour IOP monitoring. The first session occurred before initiating treatment of newly diagnosed patients or after a four-week washout in patients already receiving medical therapy. The second session occurred after four weeks or more of travoprost treatment. The third session was performed 41 to 63 hours after the last travoprost dose. RESULTS: IOP lowering persisted after omission of one to two doses. Between 41 to 63 hours after the last dose, diurnal IOP reduction was attenuated, but nocturnal IOP reduction sustained. CONCLUSIONS: IOP lowering effect after omission of one to two doses of travoprost is attenuated in the diurnal period but sustained in the nocturnal period, the time corresponding to the highest baseline habitual IOP.

Aged↗
PubMed2006

Human serum reduces mitomycin-C cytotoxicity in human tenon's fibroblasts.

PURPOSE: To determine the effect of human serum factors on mitomycin-C (MMC) cytotoxicity in cultured human subconjunctival Tenon's capsule fibroblasts. METHODS: Fibroblast monolayers were treated with 5-minute applications of mitomycin-C (0.4 mg/mL) and incubated in culture medium with or without additional human serum. Fibroblast apoptosis was quantified by direct cell counts based on nuclear morphology, flow cytometry with annexin-V/propidium iodide, and a lactate dehydrogenase release assay. The number of viable fibroblasts and fibroblast proliferation were measured with a colorimetric MTT assay and by bromodeoxyuridine (BrdU) labeling. RESULTS: Mitomycin-C induced significant levels of fibroblast apoptosis. The addition of human serum resulted in a 40% reduction in MMC-induced fibroblast apoptosis (range, 31.3%-55.3%; P = 0.021) as determined by nuclear morphology and a 32.4% reduction measured by annexin-V/PI. There was a corresponding dose-dependent increase in the number of viable fibroblasts. Serum did not restore proliferation in MMC-treated fibroblasts. CONCLUSIONS: Factors present in human serum reduce MMC cytotoxicity in cultured human Tenon's fibroblasts. Human serum increased the number of viable fibroblasts by inhibiting MMC-induced fibroblast apoptosis. Serum factors access aqueous humor after trabeculectomy and may therefore influence the clinical outcome of MMC treatment.

Annexin A5↗
PubMed2006

Distribution of optic disc parameters measured by OCT: findings from a population-based study of 6-year-old Australian children.

PURPOSE: To study the distribution of optic disc, cup, and neural rim size by ocular and demographic variables in a population-based sample of 6-year-old children. METHODS: The Sydney Childhood Eye Study examined 1765 of 2238 eligible 6-year-old children (78.9%) from 34 randomly selected Sydney schools during 2003 to 2004. Comprehensive standardized eye examination included cycloplegic autorefraction, optical biometry and "fast optic disc" scans performed using optical coherence tomography. RESULTS: Scans of adequate quality were available for 1309 children (75% of participants), with 70% aged 6 years; 50.9% were boys. Mean (+/- SD) horizontal and vertical disc diameter and disc area was 1.53 +/- 0.21 mm, 1.79 +/- 0.28 mm, and 2.20 +/- 0.39 mm(2), respectively. Corresponding cup dimensions were 0.70 +/- 0.28 mm, 0.73 +/- 0.27 mm, and 0.48 +/- 0.32 mm(2). A definable optic cup was absent in 7.4%, 87% of whom were European white. Cup-to-disc diameter ratios were 0.46 +/- 0.16 horizontally and 0.42 +/- 0.15 vertically, whereas cup-to-disc area ratio was 0.22 +/- 0.13. Mean +/- SD neural rim area was 1.76 +/- 0.44 mm(2) and increased with disc size (Pearson correlation = 0.68, P < 0.0001). Horizontal and vertical average nerve widths were 0.36 +/- 0.05 and 0.28 +/- 0.05 mm, respectively. In analyses adjusting for potential confounders, disc area increased significantly with axial length (P(trend) < 0.0001) and refraction (P(trend) = 0.02). Rim area increased only with axial length (P(trend) = 0.01). There were no gender differences, except for average nerve width, marginally greater in boys. Most disc and cup dimensions were significantly larger in East-Asian than European white and Middle Eastern children. CONCLUSIONS: Disc, cup, and neural rim parameters were generally normally distributed in this young population. Axial length appeared to be a stronger determinant of disc and rim size than refraction. Some ethnic but not gender differences were demonstrated for most parameters.

Australia↗
PubMed2005

Validation of a predictive model to estimate the risk of conversion from ocular hypertension to glaucoma.

OBJECTIVES: To develop and validate a predictive model to estimate the risk of conversion from ocular hypertension to glaucoma. METHODS: Predictive models for the 5-year risk of conversion to glaucoma were derived from the results of the Ocular Hypertension Treatment Study (OHTS). The performance of these models was assessed in an independent population of 126 subjects with ocular hypertension from a longitudinal study (Diagnostic Innovations in Glaucoma Study [DIGS]). The performance of the OHTS-derived models was assessed in the DIGS cohort according to equality of regression coefficients, discrimination (c-index), and calibration. RESULTS: Thirty-one patients (25%) developed glaucoma during follow-up. Hazard ratios for DIGS- and OHTS-derived predictive models were similar for age, intraocular pressure, central corneal thickness, vertical cup-disc ratio, and pattern standard deviation but were significantly different for the presence of diabetes mellitus. When applied to the DIGS population, the OHTS-derived predictive models had reasonably good discrimination (c-indexes of 0.68 [full model] and 0.73 [reduced model]) and calibration. CONCLUSIONS: The OHTS-derived predictive models performed well in assessing the risk of glaucoma development in an independent population of untreated subjects with ocular hypertension. A risk scoring system was developed that allows calculation of the 5-year risk of glaucoma development for an individual patient.

Disease Progression↗
PubMed2005

Argon laser iridoplasty in the treatment of plateau-like iris configuration as result of numerous ciliary body cysts.

PURPOSE: To report the use of argon laser peripheral iridoplasty in the treatment of plateau-like iris configuration as a result of iris and ciliary body cysts. DESIGN: Case report. METHODS: A 43-year-old male with plateau iris syndrome was demonstrated by high frequency ultrasound biomicroscopy (UBM), to have numerous iris and ciliary body cysts. Bilateral argon laser peripheral iridoplasty was performed. RESULTS: Argon laser iridoplasty opened the drainage angle in both eyes. CONCLUSION: Argon laser iridoplasty is an effective and safe treatment for plateau iris syndrome and may also prove valuable in the treatment of plateau-like iris configuration resulting from iridociliary cysts.

Adult↗
PubMed2005

Glaucoma medication and aqueous humor dynamics.

PURPOSE OF REVIEW: This review evaluates current concepts regarding the effects of glaucoma medication on aqueous humor dynamics and the impact of this on intraocular pressure control and drug selection in clinical practice. RECENT FINDINGS: Calculations based on the Friedenwald and Goldmann equations have predicted that glaucoma medications that increase pressure-sensitive aqueous outflow will dampen intraocular pressure spikes and therefore may be advantageous over drugs that do not increase outflow facility. SUMMARY: Further experimental research is required to verify the influence of increased outflow facility on intraocular pressure fluctuation and the effect of this on glaucoma progression.

Animals↗
PubMed2005

Unsupervised machine learning with independent component analysis to identify areas of progression in glaucomatous visual fields.

PURPOSE: To determine whether a variational Bayesian independent component analysis mixture model (vB-ICA-mm), a form of unsupervised machine learning, can be used to identify and quantify areas of progression in standard automated perimetry fields. METHODS: In an earlier study, it was shown that a model using vB-ICA-mm can separate normal fields from fields with six different patterns of visual field loss related to glaucomatous optic neuropathy (GON) along maximally independent axes. In the present study, an independent group of 191 patient eyes (66 with ocular hypertension (OHT), 12 with suspected glaucoma by field, 61 with suspected glaucoma by disc, and 52 with glaucoma) with five or more standard visual fields under observation for a mean of 6.24 +/- 2.65 years and 8.11 +/- 2.42 visual fields were evaluated with the vB-ICA-mm. In addition, eyes with progressive GON (PGON) were identified (n = 39). Each participant had a series of fields tested, with each field entered independently and placed along the axes of the previously developed model. This allowed change in one pattern of visual field defect (along one axis) to be assessed relative to results other areas of that same field (no change along other axes). Progression was based on a slope falling outside the 5th and the 95th percentile limits of all slopes, with at least two axes not showing such a deviation in a given individual's series of fields. Fields were also scored using Advanced Glaucoma Intervention Study (AGIS) and the Early Manifest Glaucoma Treatment Trial (EMGT) criteria. RESULTS: Thirty-two of 191 eyes progressed on vB-ICA-mm by this definition. Of the 32, 22 had field loss at baseline, 7 had only GON, 3 were OHTs and 12 were from the 39 eyes (31%) with PGON. The vB-ICA-mm identified a higher percentage of progressing eyes in each diagnostic category than did AGIS or and the EMGT. CONCLUSIONS: The vB-ICA-mm can quantitatively identify progression in eyes with glaucoma by evaluating change in one or more patterns of the visual field loss while other areas or patterns remain stable. This may enable each eye to contribute to the determination of whether change is caused by true progression or by variability.

Adult↗
PubMed2005

Interaction with collagen IV protects lens epithelial cells from Fas-dependent apoptosis by stimulating the production of soluble survival factors.

PURPOSE: To investigate the sensitivity of lens epithelial cells (LECs) to Fas-dependent apoptosis and to determine the role of interaction with the extracellular matrix (ECM) in the regulation of Fas-dependent apoptosis. METHODS: Sensitivity to Fas-mediated apoptosis of primary human LECs and HLE-B3 LECs cultured on different substrates was determined by Hoechst staining after incubation with Fas-stimulating or control IgM. Fas expression was determined by Western blot analysis. Effects of varied cell density and conditioned media from HLE-B3 cells cultured on different substrates on the Fas sensitivity of HLE-B3 cells cultured on tissue culture (TC) plastic were determined. RESULTS: Primary LECs cultured as free-floating anterior capsulotomy specimens were resistant to Fas-dependent apoptosis. The LE cell line, HLE-B3, was sensitive to Fas-dependent apoptosis when cultured on TC plastic but not on lens capsule. Culture on collagen IV, but not on laminin, rendered HLE-B3 cells resistant to Fas-dependent apoptosis, although Fas was still expressed. Primary LECs cultured on TC plastic after migration from lens capsule explants were resistant to Fas-dependent apoptosis if the lens capsule and attached cells were still present, but not if the lens capsule had been removed. Conditioned medium from LECs cultured on collagen IV, but not TC plastic, protected cells cultured on TC plastic from Fas-dependent apoptosis. The protective effect of culture on collagen IV diminished with decreasing cell density. CONCLUSIONS: LECs are protected from Fas-dependent apoptosis by interaction with collagen IV. Soluble factors released by the LECs cultured on collagen IV protect LECs from Fas-dependent apoptosis.

Apoptosis↗
PubMed2005

Effect of bimatoprost on intraocular pressure in prostaglandin FP receptor knockout mice.

PURPOSE: To determine the effect of bimatoprost on intraocular pressure in the prostaglandin FP receptor knockout mouse. METHODS: The IOP response to a single 1.2-microg (4 microL) dose of bimatoprost was measured in the treated and untreated fellow eyes of homozygote (FP+/+, n = 9) and heterozygote (FP+/-, n = 10) FP-knockout mice, as well as in wild-type C57BL/6 mice (FP+/+, n = 20). Serial IOP measurements were also performed after topical bimatoprost in a separate generation of homozygous FP-knockout mice and wild-type littermate control animals (n = 4 per group). Aqueous humor protein concentrations were measured to establish the state of the blood-aqueous barrier. Tissue, aqueous humor and vitreous concentrations of bimatoprost, latanoprost, and their C-1 free acids were determined by liquid chromatography and tandem mass spectrometry. RESULTS: A significant reduction in IOP was observed in the bimatoprost-treated eye of wild-type mice at 2 hours, with a mean difference and 95% confidence interval (CI) of the difference in means of -1.33 mm Hg (-0.81 to -1.84). Bimatoprost did not lead to a significant reduction in IOP in either the heterozygous knockout -0.36 mm Hg (-0.82 to +0.09) or homozygous FP-knockout mice 0.25 mm Hg (-0.38 to +0.89). The lack of an IOP response in the FP-knockout mice was not a consequence of blood-aqueous barrier breakdown, as there was no significant difference in aqueous humor protein concentration between treated and fellow eyes. Tissue and aqueous humor concentrations of bimatoprost, latanoprost, and their C-1 free acids indicate that latanoprost, but not bimatoprost, is hydrolyzed in the mouse eye after topical administration. CONCLUSIONS: An intact FP receptor gene is critical to the IOP response to bimatoprost in the mouse eye.

Amides↗
PubMed2004

Water-mediated lysis of lens epithelial cells attached to lens capsule.

PURPOSE: To investigate the effect of distilled deionized water (DDW) on lens epithelial cells (LECs) attached to the lens capsule. SETTING: Wound Healing Research Laboratory, Center for Vision Research, Westmead Hospital, Sydney, NSW, Australia. METHODS: Anterior capsulotomy specimens taken during routine cataract surgery were divided in half. One half was immersed in DDW and the other half in culture medium (control) for 1 to 5 minutes and photographed at intervals by phase-contrast microscopy. In further experiments, the capsules were exposed to DDW for 1 or 2 minutes and placed in culture for 1 week to determine whether LECs survive treatment and are capable of repopulating the lens capsule. RESULTS: Distilled-deionized water induced marked swelling of the cytoplasm within 60 seconds of treatment. At 120 seconds, there was disruption of the plasma membranes, with few intact cells remaining. In the control capsules, confluent monolayers of LECs covered the entire capsule surface with a halo of LECs growing on the surrounding plastic well. Viable LECs were observed in 1 of 3 capsules treated for 1 minute with DDW. These did not reach confluence or grow off the capsule onto the surrounding well. No viable LECs were seen on capsules exposed to DDW for 2 minutes. CONCLUSIONS: Short exposure of LECs to DDW induced extensive and rapid cell lysis. Distilled-deonized water may be a useful agent for instillation in the capsular bag during sealed-capsule irrigation to prevent posterior capsule opacification.

Cataract Extraction↗
PubMed2004

Effect of latanoprost on outflow facility in the mouse.

PURPOSE: To assess the early effect of latanoprost on outflow facility and aqueous humor dynamics in the mouse. METHODS: Aqueous humor dynamics in NIH Swiss White mice were assessed with an injection and aspiration system, using fine glass microneedles. A single 200-ng (4 microL) dose of latanoprost was applied to one eye 2 hours before measurement. The fellow eye served as a control. Intraocular pressure (IOP) was measured by using an established microneedle procedure. Outflow facility (C) was determined by constant-pressure perfusion measurements obtained at two different IOPs. Aqueous humor flow (Fa) was determined by a dilution method using rhodamine-dextran. Conventional and uveoscleral outflow (Fc and Fu) were calculated by the Goldmann equation. RESULTS: Average IOP, Fa, and C of control eyes were 15.7 +/- 1.0 mm Hg, 0.144 +/- 0.04 microL/min (mean +/- SD, n = 8), and 0.0053 +/- 0.0014 microL/min per mm Hg (n = 21), respectively. Average IOP, Fa, and C of treated eyes were 14.0 +/- 0.8 mm Hg, 0.138 +/- 0.04 microL/min (n = 8 for each), and 0.0074 +/- 0.0016 microL/min per mm Hg (n = 21), respectively. The differences between treated and control eyes were significant for IOP and total outflow facility only. CONCLUSIONS: These data indicate that the early hypotensive effect of latanoprost in the mouse eye is associated with a significant increase in total outflow facility. Alterations in the aqueous dynamics induced by latanoprost can be measured reproducibly in the mouse and may provide a useful model for further determining the mechanism by which latanoprost reduces IOP and alters outflow facility.

Animals↗
PubMed2004

Confocal scanning laser ophthalmoscopy classifiers and stereophotograph evaluation for prediction of visual field abnormalities in glaucoma-suspect eyes.

PURPOSE: To determine whether Heidelberg Retina Tomograph (HRT; Heidelberg Engineering, Dossenheim, Germany) classification techniques and investigational support vector machine (SVM) analyses can detect optic disc abnormalities in glaucoma-suspect eyes before the development of visual field abnormalities. METHODS: Glaucoma-suspect eyes (n = 226) were classified as converts or nonconverts based on the development of repeatable (either two or three consecutive) standard automated perimetry (SAP)-detected abnormalities over the course of the study (mean follow-up, approximately 4.5 years). Hazard ratios for development of SAP abnormalities were calculated based on baseline classification results, follow-up time, and end point status (convert, nonconvert). Classification techniques applied were HRT classification (HRTC), Moorfields Regression Analysis, forward-selection optimized SVM (SVM fwd) and backward elimination-optimized SVM (SVM back) analysis of HRT data, and stereophotograph assessment. RESULTS: Univariate analyses indicated that all classification techniques were predictors of the development of two repeatable abnormal SAP results, with hazards ratios (95% confidence interval [CI]) ranging from 1.32 (1.00-1.75) for HRTC to 2.0 (1.48-2.76) for stereophotograph assessment (all P < or = 0.05). Only SVM (SVM fwd and SVM back) analysis of HRT data and stereophotograph assessment were univariate predictors of the development of three repeatable abnormal SAP results, with hazard ratios (95% CI) ranging from 1.73 (1.16-2.82) for SVM fwd to 1.82 (1.19-3.12) for SVM back (both P < 0.007). Multivariate analyses including each classification technique individually in a model with age, baseline SAP pattern standard deviation [PSD], and baseline IOP indicated that all classification techniques except HRTC (P = 0.06) were predictors of the development of two repeatable abnormal SAP results with hazards ratios ranging from 1.30 (0.99, 1.73) for HRTC to 1.90 (1.37, 2.69) for stereophotograph assessment. Only SVM (SVM fwd and SVM back) analysis of HRT data and stereophotograph assessment were significant predictors of the development of three repeatable abnormal SAP results in multivariate analyses; hazard ratios of 1.57 (1.03, 2.59) and 1.70 (1.18, 2.51), respectively. SAP PSD was a significant predictor of two repeatable abnormal SAP results in multivariate models with all classification techniques, with hazard ratios ranging from 3.31 (1.39, 7.89) to 4.70 (2.02, 10.93) per 1-dB increase. CONCLUSIONS: HRT classifications techniques and stereophotograph assessment can detect optic disc topography abnormalities in glaucoma-suspect eyes before the development of SAP abnormalities. These data support strongly the importance of optic disc examination for early glaucoma diagnosis.

Adult↗
PubMed2004

Effect of latanoprost on intraocular pressure in mice lacking the prostaglandin FP receptor.

PURPOSE: To determine whether latanoprost lowers IOP in prostaglandin FP receptor knockout mice. METHODS: Mean IOP difference between treated and untreated fellow eyes was measured on three separate occasions, 2 hours after a 200-ng dose of latanoprost to the right eye of homozygous (n = 9) and heterozygous (n = 15) FP knockout mice. C57BL/6 (n = 10) and NIH Swiss white mice (n = 17), which have normal FP receptor expression, provided the control population. The investigator was masked to the genotype of the FP knockout mice at the time of IOP measurement. RESULTS: Latanoprost had no effect on IOP in the homozygous FP knockout mice, with an average difference in IOP between treated and untreated fellow eyes of +0.25 mm Hg and a 95% confidence interval (CI) for the difference between means of -0.019 to +0.69. In contrast, latanoprost reduced IOP in the treated eye of the heterozygous FP knockout, C57BL/6, and Swiss white mice with mean differences and 95% CI of the difference in means of -0.52 (-0.91 to -0.14), -1.38 (-2.1 to -0.70), and -1.29 (-1.78 to -0.79) mm Hg, respectively. CONCLUSIONS: FP receptor signaling plays a crucial role in the early IOP response to latanoprost in the mouse eye.

Animals↗
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↗
PubMedDate not supplied

Optic disk size and glaucoma.

Assessment of optic disk size is an important, but often overlooked, component of the diagnostic evaluation for glaucoma. Measured values of optic disk size vary with the measurement technique utilized. Available methods for disk size measurement and their respective strengths and limitations will be discussed. Further, actual disk size varies with race and possibly other demographic characteristics. Disk size is also associated with variation of specific anatomical structures of the optic nerve head and the retinal nerve fiber layer. These disk size- dependent variations may influence the susceptibility to glaucoma or the likelihood of glaucoma diagnosis. This manuscript reviews the published evidence relating to disk size and glaucoma.

Age Factors↗