Imperial College London

ProfessorDarrylOverby

Faculty of EngineeringDepartment of Bioengineering

Professor of Mechanobiology
 
 
 
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Contact

 

+44 (0)20 7594 6376d.overby

 
 
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Location

 

3.07Bessemer BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

166 results found

Overby DR, Braakman S, Spenlehauer A, Rodrigues JR, Teal C, Read AT, Stamer WD, Ethier CRet al., 2017, Stretch-Dependent Pore Formation in Glaucomatous Schlemm's Canal Cells, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404

Conference paper

Chang JYH, Chow LW, Dismuke WM, Ethier CR, Stevens MM, Stamer WD, Overby Det al., 2017, Peptide-functionalized fluorescent particles for in situ detection of nitric oxide via peroxynitrite-mediated nitration, Advanced Healthcare Materials, Vol: 6, ISSN: 2192-2640

Nitric oxide (NO) is a free radical signaling molecule that plays a crucial role in modulating physiological homeostasis across multiple biological systems. NO dysregulation is linked to the pathogenesis of multiple diseases; therefore, its quantification is important for understanding pathophysiological processes. The detection of NO is challenging, typically limited by its reactive nature and short half-life. Additionally, the presence of interfering analytes and accessibility to biological fluids in the native tissues make the measurement technically challenging and often unreliable. Here, a bio-inspired peptide-based NO sensor is developed, which detects NO-derived oxidants, predominately peroxynitrite-mediated nitration of tyrosine residues. It is demonstrated that these peptide-based NO sensors can detect peroxynitrite-mediated nitration in response to physiological shear stress by endothelial cells in vitro. Using the peptide-conjugated fluorescent particle immunoassay, peroxynitrite-mediated nitration activity with a detection limit of ≈100 × 10−9m is detected. This study envisions that the NO detection platform can be applied to a multitude of applications including monitoring of NO activity in healthy and diseased tissues, localized detection of NO production of specific cells, and cell-based/therapeutic screening of peroxynitrite levels to monitor pronitroxidative stress in biological samples.

Journal article

Chandrawati R, Chang J, Reina-Torres E, Jumeaux C, Sherwood JM, Stamer WD, Zelikin AN, Overby DR, Stevens MMet al., 2017, Localized and controlled delivery of nitric oxide to the conventional outflow pathway via enzyme biocatalysis: towards therapy for Glaucoma, Advanced Materials, Vol: 29, ISSN: 1521-4095

Nitric oxide (NO) has been shown to lower intraocular pressure (IOP), however its therapeutic effects on outflow physiology are location- and dose-dependent. Here, a NO delivery platform that directly targets the resistance-generating region of the conventional outflow pathway and locally liberates a controlled dose of NO is reported. An increase in outflow facility (decrease in IOP) is demonstrated in mouse model.

Journal article

Overby DR, 2017, VEGF as a paracrine regulator of conventional outflow facility, Investigative Ophthalmology & Visual Science, Vol: 58, Pages: 1899-1908, ISSN: 1552-5783

Purpose: Vascular endothelial growth factor (VEGF) regulates microvascular endothelial permeability, and the permeability of Schlemm's canal (SC) endothelium influences conventional aqueous humor outflow. We hypothesize that VEGF signaling regulates outflow facility.Methods: We measured outflow facility (C) in enucleated mouse eyes perfused with VEGF-A164a, VEGF-A165b, VEGF-D, or inhibitors to VEGF receptor 2 (VEGFR-2). We monitored VEGF-A secretion from human trabecular meshwork (TM) cells by ELISA after 24 hours of static culture or cyclic stretch. We used immunofluorescence microscopy to localize VEGF-A protein within the TM of mice.Results: VEGF-A164a increased C in enucleated mouse eyes. Cyclic stretch increased VEGF-A secretion by human TM cells, which corresponded to VEGF-A localization in the TM of mice. Blockade of VEGFR-2 decreased C, using either of the inhibitors SU5416 or Ki8751 or the inactive splice variant VEGF-A165b. VEGF-D increased C, which could be blocked by Ki8751.Conclusions: VEGF is a paracrine regulator of conventional outflow facility that is secreted by TM cells in response to mechanical stress. VEGF affects facility via VEGFR-2 likely at the level of SC endothelium. Disruption of VEGF signaling in the TM may explain why anti-VEGF therapy is associated with decreased outflow facility and sustained ocular hypertension.

Journal article

Wen JC, Reina-Torres E, Sherwood JM, Challa P, Liu KC, Li G, Chang JYH, Cousins SW, Schuman SG, Mettu PS, Stamer WD, Overby DR, Allingham RRet al., 2017, Intravitreal anti-VEGF injections reduce aqueous outflow facility in patients with neovascular age-related macular degeneration, Investigative Ophthalmology & Visual Science, Vol: 58, Pages: 1893-1898, ISSN: 0146-0404

Purpose: We assess the effect of intravitreal anti-VEGF injections on tonographic outflow facility.Methods: Patients with age-related macular degeneration who had received unilateral intravitreal anti-VEGF injections were recruited into two groups, those with ≤10 and those with ≥20 total anti-VEGF injections. Intraocular pressure and tonographic outflow facility of injected and uninjected fellow eyes were measured and compared between groups. Risk factors for development of reduced outflow facility also were assessed.Results: Outflow facility was 12% lower in the injected eyes of patients who received ≥20 anti-VEGF injections, compared to contralateral uninjected eyes (P = 0.02). In contrast, there was no facility reduction for patients with ≤10 anti-VEGF injections (P = 0.4). In patients with ocular hypertension in the uninjected eye (IOP > 21 mm Hg, n = 5), the outflow facility of injected eyes was on average 46% lower (P = 0.01) than in the uninjected fellow eyes. This was significantly greater than the difference observed in patients with IOP ≤ 21 mm Hg in the uninjected eye (P = 2 × 10−4). In patients with ocular hypertension in the injected eye (n = 6) the differences in facility and IOP between contralateral eyes were significantly greater than in patients with IOP ≤ 21 mm Hg in the injected eye (P = 2 × 10−4 and P = 7 × 10−4, respectively).Conclusions: Chronic anti-VEGF injections significantly reduce outflow facility in patients with AMD. The greatest facility reduction is observed in patients with baseline ocular hypertension. Ophthalmologists who administer anti-VEGF injections should be aware of these findings and monitor patients closely for changes in IOP or evidence of glaucoma, especially in those with pre-existing ocular hypertension.

Journal article

O'Callaghan J, Crosbie DE, Cassidy PS, Sherwood JM, Fluegel-Koch C, Luetjen-Drecoll E, Humphries MM, Reina-Torres E, Wallace D, Kiang A-S, Campbell M, Stamer WD, Overby DR, O'Brien C, Tam LCS, Humphries Pet al., 2017, Therapeutic potential of AAV-mediated MMP-3 secretion from corneal endothelium in treating glaucoma, HUMAN MOLECULAR GENETICS, Vol: 26, Pages: 1230-1246, ISSN: 0964-6906

Intraocular pressure (IOP) is maintained as a result of the balance between production of aqueous humour (AH) by the ciliary processes and hydrodynamic resistance to its outflow through the conventional outflow pathway comprising the trabecular meshwork (TM) and Schlemm’s canal (SC). Elevated IOP, which can be caused by increased resistance to AH outflow, is a major risk factor for open-angle glaucoma. Matrix metalloproteinases (MMPs) contribute to conventional aqueous outflow homeostasis in their capacity to remodel extracellular matrices, which has a direct impact on aqueous outflow resistance and IOP. We observed decreased MMP-3 activity in human glaucomatous AH compared to age-matched normotensive control AH. Treatment with glaucomatous AH resulted in significantly increased transendothelial resistance of SC endothelial and TM cell monolayers and reduced monolayer permeability when compared to control AH, or supplemented treatment with exogenous MMP-3.Intracameral inoculation of AAV-2/9 containing a CMV-driven MMP-3 gene (AAV-MMP-3) into wild type mice resulted in efficient transduction of corneal endothelium and an increase in aqueous concentration and activity of MMP-3. Most importantly, AAV-mediated expression of MMP-3 increased outflow facility and decreased IOP, and controlled expression using an inducible promoter activated by topical administration of doxycycline achieved the same effect. Ultrastructural analysis of MMP-3 treated matrices by transmission electron microscopy revealed remodelling and degradation of core extracellular matrix components. These results indicate that periodic induction, via use of an eye drop, of AAV-mediated secretion of MMP-3 into AH could have therapeutic potential for those cases of glaucoma that are sub-optimally responsive to conventional pressure-reducing medications.

Journal article

Tam LC, Reina-Torres E, Sherwood JM, Cassidy PS, Crosbie DE, Lütjen-Drecoll E, Flügel-Koch C, Perkumas K, Humphries MM, Kiang AS, O'Callaghan J, Callanan JJ, Read AT, Ethier CR, O'Brien C, Lawrence M, Campbell M, Stamer WD, Overby DR, Humphries Pet al., 2017, Enhancement of outflow facility in the murine eye by targeting selected tight-junctions of Schlemm's canal endothelia, Scientific Reports, Vol: 7, ISSN: 2045-2322

The juxtacanalicular connective tissue of the trabecular meshwork together with inner wall endothelium of Schlemm’s canal (SC) provide the bulk of resistance to aqueous outflow from the anterior chamber. Endothelial cells lining SC elaborate tight junctions (TJs), down-regulation of which may widen paracellular spaces between cells, allowing greater fluid outflow. We observed significant increase in paracellular permeability following siRNA-mediated suppression of TJ transcripts, claudin-11, zonula-occludens-1 (ZO-1) and tricellulin in human SC endothelial monolayers. In mice claudin-11 was not detected, but intracameral injection of siRNAs targeting ZO-1 and tricellulin increased outflow facility significantly. Structural qualitative and quantitative analysis of SC inner wall by transmission electron microscopy revealed significantly more open clefts between endothelial cells treated with targeting, as opposed to non-targeting siRNA. These data substantiate the concept that the continuity of SC endothelium is an important determinant of outflow resistance, and suggest that SC endothelial TJs represent a specific target for enhancement of aqueous movement through the conventional outflow system.

Journal article

Sory DR, Areias AC, Overby DR, Proud WGet al., 2017, Novel method to dynamically load cells in 3D-hydrogels culture for blast injury studies, 19th Biennial American-Physical-Society (APS) Conference on Shock Compression of Condensed Matter (SCCM), Publisher: AMER INST PHYSICS, ISSN: 0094-243X

Conference paper

Bertrand JA, Sherwood LM, Li G, Stainer WD, Overby DRet al., 2016, Sustained local delivery of dexamethasone using nanoparticles for steroid-induced ocular hypertension in mice, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: Association for Research in Vision and Ophthalmology, ISSN: 1552-5783

Conference paper

Madekurozwa M, Sherwood JM, Reina-Torres E, Bertrand JA, Overby DRet al., 2016, Pressure-independent outflow in <i>ex vivo</i> mouse eyes, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404

Conference paper

O'Callaghan J, Crosbie D, Cassidy P, Humphries MM, Kiang A-S, Sherwood JM, Overby DR, Starner WD, Tam L, Humphries Pet al., 2016, AAV-mediated MMP3 expression from corneal endothelium as a targeted gene therapy approach for glaucoma, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404

Conference paper

Crosbie D, Keaney J, Sherwood JM, Overby DR, Stamer WD, Tam L, Humphries Pet al., 2016, Assessment of age-related eye morphology and aqueous humor flow dynamics in the DBA/2J mouse model of pigmentary glaucoma using ocular MRI and anterior chamber iPerfusion systems, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404

Conference paper

Reina-Torres E, Sherwood JM, Overby DR, 2016, The role of VEGF on outflow facility in mice with glucocorticoid-induced ocular hypertension, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404

Conference paper

Ashpole NE, Mukherjee D, Li G, Maccarini P, Sherwood JM, Ethier CR, Overby DR, Farsiu S, Stamer WDet al., 2016, IOP-induced Changes in Schlemm's Canal Dimensions and the Relation to Shear Stress, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404

Conference paper

Li G, Mukherjee D, Navarro I, Ashpole NE, Sherwood JM, Chang J, Overby DR, Yuan F, Gonzalez P, Kopczynski CC, Farsiu S, Stamer WDet al., 2016, Visualization of conventional outflow tissue responses to netarsudil in living mouse eyes, European Journal of Pharmacology, Vol: 787, Pages: 20-31, ISSN: 0014-2999

Visual impairment due to glaucoma currently impacts 70 million people worldwide. While disease progression can be slowed or stopped with effective lowering of intraocular pressure, current medical treatments are often inadequate. Fortunately, three new classes of therapeutics that target the diseased conventional outflow tissue responsible for ocular hypertension are in the final stages of human testing. The rho kinase inhibitors have proven particularly efficacious and additive to current therapies. Unfortunately, non-contact technology that monitors the health of outflow tissue and its response to conventional outflow therapy is not available clinically. Using optical coherence tomographic (OCT) imaging and novel segmentation software, we present the first demonstration of drug effects on conventional outflow tissues in living eyes. Topical netarsudil (formerly AR-13324), a rho kinase/ norepinephrine transporter inhibitor, affected both proximal (trabecular meshwork and Schlemm’s Canal) and distal portions (intrascleral vessels) of the mouse conventional outflow tract. Hence, increased perfusion of outflow tissues was reliably resolved by OCT as widening of the trabecular meshwork and significant increases in cross-sectional area of Schlemm’s canal following netarsudil treatment. These changes occurred in conjunction with increased outflow facility, increased speckle variance intensity of outflow vessels, increased tracer deposition in conventional outflow tissues and decreased intraocular pressure. This is the first report using live imaging to show real-time drug effects on conventional outflow tissues and specifically the mechanism of action of netarsudil in mouse eyes. Advancements here pave the way for development of a clinic-friendly OCT platform for monitoring glaucoma therapy.

Journal article

Martella A, Silvestri C, Maradonna F, Gioacchini G, Allara M, Radaelli G, Overby DR, Di Marzo V, Carnevali Oet al., 2016, Bisphenol A induces fatty liver by an endocannabinoid-mediated positive feedback loop, Endocrinology, Vol: 157, Pages: 1751-1763, ISSN: 0013-7227

The xenoestrogen bisphenol A (BPA) is a widespread plasticizer detectable within several ecosystems. BPA is considered a metabolic disruptor, affecting different organs; however, little is known about its mechanism of action in the liver, in which it triggers triglyceride accumulation. Adult zebrafish (Danio rerio) exposed to BPA developed hepatosteatosis, which was associated with an increase in the liver levels of the obesogenic endocannabinoids 2-arachidonoylglycerol and anandamide and a concomitant decrease in palmitoylethanolamide. These changes were associated with variations in the expression of key endocannabinoid catabolic and metabolic enzymes and an increase in the expression of the endocannabinoid receptor cnr1. Acute and chronic in vitro treatments with nano- and micromolar BPA doses showed increased anandamide levels in line with decreased activity of fatty acid amide hydrolase, the main anandamide hydrolytic enzyme, and induced triglyceride accumulation in HHL-5 cells in a CB1-dependent manner. We conclude that BPA is able to produce hepatosteatosis in zebrafish and human hepatocytes by up-regulating the endocannabinoid system.

Journal article

Dismuke WM, Overby DR, Civan MM, Stamer WDet al., 2016, The Value of Mouse Models for Glaucoma Drug Discovery, Journal of Ocular Pharmacology and Therapeutics, Vol: 32, Pages: 486-487, ISSN: 1080-7683

Journal article

Sherwood JM, Reina-Torres E, Bertrand J, Rowe B, Overby DRet al., 2016, Measurement of outflow facility using iPerfusion, PLoS One, Vol: 11, Pages: 1-29, ISSN: 1932-6203

Elevated intraocular pressure (IOP) is the predominant risk factor for glaucoma, and reducing IOP is the only successful strategy to prevent further glaucomatous vision loss. IOP is determined by the balance between the rates of aqueous humour secretion and outflow, and a pathological reduction in the hydraulic conductance of outflow, known as outflow facility, is responsible for IOP elevation in glaucoma. Mouse models are often used to investigate the mechanisms controlling outflow facility, but the diminutive size of the mouse eye makes measurement of outflow technically challenging. In this study, we present a new approach to measure and analyse outflow facility using iPerfusion™, which incorporates an actuated pressure reservoir, thermal flow sensor, differential pressure measurement and an automated computerised interface. In enucleated eyes from C57BL/6J mice, the flow-pressure relationship is highly non-linear and is well represented by an empirical power law model that describes the pressure dependence of outflow facility. At zero pressure, the measured flow is indistinguishable from zero, confirming the absence of any significant pressure independent flow in enucleated eyes. Comparison with the commonly used 2-parameter linear outflow model reveals that inappropriate application of a linear fit to a non-linear flow-pressure relationship introduces considerable errors in the estimation of outflow facility and leads to the false impression of pressure-independent outflow. Data from a population of enucleated eyes from C57BL/6J mice show that outflow facility is best described by a lognormal distribution, with 6-fold variability between individuals, but with relatively tight correlation of facility between fellow eyes. iPerfusion represents a platform technology to accurately and robustly characterise the flow-pressure relationship in enucleated mouse eyes for the purpose of glaucoma research and with minor modifications, may be applied in vivo to mice

Journal article

Johnson M, McLaren JW, Overby DR, 2016, Unconventional aqueous humor outflow: A review, EXPERIMENTAL EYE RESEARCH, Vol: 158, Pages: 94-111, ISSN: 0014-4835

Aqueous humor flows out of the eye primarily through the conventional outflow pathway that includes the trabecular meshwork and Schlemm's canal. However, a fraction of aqueous humor passes through an alternative or ‘unconventional’ route that includes the ciliary muscle, supraciliary and suprachoroidal spaces. From there, unconventional outflow may drain through two pathways: a uveoscleral pathway where aqueous drains across the sclera to be resorbed by orbital vessels, and a uveovortex pathway where aqueous humor enters the choroid to drain through the vortex veins. We review the anatomy, physiology and pharmacology of these pathways. We also discuss methods to determine unconventional outflow rate, including direct techniques that use radioactive or fluorescent tracers recovered from tissues in the unconventional pathway and indirect methods that estimate unconventional outflow based on total outflow over a range of pressures. Indirect methods are subject to a number of assumptions and generally give poor agreement with tracer measurements. We review the variety of animal models that have been used to study conventional and unconventional outflow. The mouse appears to be a promising model because it captures several aspects of conventional and unconventional outflow dynamics common to humans, although questions remain regarding the magnitude of unconventional outflow in mice. Finally, we review future directions. There is a clear need to develop improved methods for measuring unconventional outflow in both animals and humans.

Journal article

Areias AC, Silvestri C, Overby DR, 2016, The Role of Compressive Load on Adipogenic Differentiation of 3T3-L1 Cells., Annual Meeting of the American-Society-for-Cell-Biology (ASCB), Publisher: AMER SOC CELL BIOLOGY, ISSN: 1059-1524

Conference paper

Braakman ST, Moore JE, Ethier CR, Overby DRet al., 2015, Transport across Schlemm's canal endothelium and the blood-aqueous barrier, Experimental Eye Research, Vol: 146, Pages: 17-21, ISSN: 0014-4835

The majority of trabecular outflow likely crosses Schlemm's canal (SC) endothelium through micron-sized pores, and SC endothelium provides the only continuous cell layer between the anterior chamber and episcleral venous blood. SC endothelium must therefore be sufficiently porous to facilitate outflow, while also being sufficiently restrictive to preserve the blood-aqueous barrier and prevent blood and serum proteins from entering the eye. To understand how SC endothelium satisfies these apparently incompatible functions, we examined how the diameter and density of SC pores affects retrograde diffusion of serum proteins across SC endothelium, i.e. from SC lumen into the juxtacanalicular tissue (JCT). Opposing retrograde diffusion is anterograde bulk flow velocity of aqueous humor passing through pores, estimated to be approximately 5 mm/s. As a result of this relatively large through-pore velocity, a mass transport model predicts that upstream (JCT) concentrations of larger solutes such as albumin are less than 1% of the concentration in SC lumen. However, smaller solutes such as glucose are predicted to have nearly the same concentration in the JCT and SC. In the hypothetical case that, rather than micron-sized pores, SC formed 65 nm fenestrae, as commonly observed in other filtration-active endothelia, the predicted concentration of albumin in the JCT would increase to approximately 50% of that in SC. These results suggest that the size and density of SC pores may have developed to allow SC endothelium to maintain the blood-aqueous barrier while simultaneously facilitating aqueous humor outflow.

Journal article

Boussommier-Calleja A, Li G, Wilson A, Ziskind T, Scinteie OE, Ashpole NE, Sherwood JM, Farsiu S, Challa P, Gonzalez P, Downs JC, Ethier CR, Stamer WD, Overby DRet al., 2015, Physical factors affecting outflow facility measurements in mice, Investigative Ophthalmology & Visual Science, Vol: 56, Pages: 8331-8339, ISSN: 1552-5783

Purpose: Mice are commonly used to study conventional outflow physiology. This study examined how physical factors (hydration, temperature, and anterior chamber [AC] deepening) influence ocular perfusion measurements in mice.Methods: Outflow facility (C) and pressure-independent outflow (Fu) were assessed by multilevel constant pressure perfusion of enucleated eyes from C57BL/6 mice. To examine the effect of hydration, seven eyes were perfused at room temperature, either immersed to the limbus in saline and covered with wet tissue paper or exposed to room air. Temperature effects were examined in 12 eyes immersed in saline at 20°C or 35°C. Anterior chamber deepening was examined in 10 eyes with the cannula tip placed in the anterior versus posterior chamber (PC). Posterior bowing of the iris (AC deepening) was visualized by three-dimensional histology in perfusion-fixed C57BL/6 eyes and by spectral-domain optical coherence tomography in living CD1 mice.Results: Exposure to room air did not significantly affect C, but led to a nonzero Fu that was significantly reduced upon immersion in saline. Increasing temperature from 20°C to 35°C increased C by 2.5-fold, more than could be explained by viscosity changes alone (1.4-fold). Perfusion via the AC, but not the PC, led to posterior iris bowing and increased outflow.Conclusions: Insufficient hydration contributes to the appearance of pressure-independent outflow in enucleated mouse eyes. Despite the large lens, AC deepening may artifactually increase outflow in mice. Temperature-dependent metabolic processes appear to influence conventional outflow regulation. Physical factors should be carefully controlled in any outflow studies involving mice.

Journal article

Chang JYH, Stamer WD, Bertrand J, Read AT, Marando CM, Ethier CR, Overby DRet al., 2015, Role of nitric oxide in murine conventional outflow physiology, American Journal of Physiology - Cell Physiology, Vol: 309, Pages: C205-C214, ISSN: 0363-6143

Elevated intraocular pressure (IOP) is the main risk factor for glaucoma. Exogenous nitric oxide (NO) decreases IOP by increasing outflow facility, but whether endogenous NO production contributes to the physiological regulation of outflow facility is unclear. Outflow facility was measured by pressure-controlled perfusion in ex vivo eyes from C57BL/6 wild-type (WT) or transgenic mice expressing human endothelial NO synthase (eNOS) fused to green fluorescent protein (GFP) superimposed on the endogenously expressed murine eNOS (eNOS-GFPtg). In WT mice, exogenous NO delivered by 100 μM S-nitroso-N-acetylpenicillamine (SNAP) increased outflow facility by 62 ± 28% (SD) relative to control eyes perfused with the inactive SNAP analog N-acetyl-d-penicillamine (NAP; n = 5, P = 0.016). In contrast, in eyes from eNOS-GFPtg mice, SNAP had no effect on outflow facility relative to NAP (−9 ± 4%, P = 0.40). In WT mice, the nonselective NOS inhibitor NG-nitro-l-arginine methyl ester (l-NAME, 10 μM) decreased outflow facility by 36 ± 13% (n = 5 each, P = 0.012), but 100 μM l-NAME had no detectable effect on outflow facility (−16 ± 5%, P = 0.22). An eNOS-selective inhibitor (cavtratin, 50 μM) decreased outflow facility by 19 ± 12% in WT (P = 0.011) and 39 ± 25% in eNOS-GFPtg (P = 0.014) mice. In the conventional outflow pathway of eNOS-GFPtg mice, eNOS-GFP expression was localized to endothelial cells lining Schlemm's canal and the downstream vessels, with no apparent expression in the trabecular meshwork. These results suggest that endogenous NO production by eNOS within endothelial cells of Schlemm's canal or downstream vessels contributes to the physiological regulation of aqueous humor outflow facility in mice, representing a viable strategy to more successfully lower IOP in glaucoma.

Journal article

Overby DR, Clark AF, 2015, Animal models of glucocorticoid-induced glaucoma, Experimental Eye Research, Vol: 141, Pages: 15-22, ISSN: 0014-4835

Glucocorticoid (GC) therapy is widely used to treat a variety of inflammatory diseases and conditions.While unmatched in their anti-inflammatory and immunosuppressive activities, GC therapy is oftenassociated with the significant ocular side effect of GC-induced ocular hypertension (OHT) and iatrogenicopen-angle glaucoma. Investigators have generated GC-induced OHT and glaucoma in at least 8 differentspecies besides man. These models mimic many features of this condition in man and providemorphologic and molecular insights into the pathogenesis of GC-OHT. In addition, there are manyclinical, morphological, and molecular similarities between GC-induced glaucoma and primary openangleglaucoma (POAG), making animals models of GC-induced OHT and glaucoma attractive modelsin which to study specific aspects of POAG.

Journal article

Schwaner SA, Sherwood JM, Snider E, Geisert EE, Overby DR, Ethier CRet al., 2015, Ocular Compliance in Mice, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404

Conference paper

Overby DR, Reina-Torres E, Wen JC, Liu K, Li G, Sherwood JM, Allingham RR, Stamer WDet al., 2015, The Effects of VEGF and anti-VEGF on Outflow Facility in Mice and Humans, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404

Conference paper

Chang JYH, Braakman ST, Mohri Z, Weinberg P, Ethier CR, Stamer WD, Overby DRet al., 2015, Colocalization of segmental outflow and endogenous eNOS activity in the conventional outflow pathway of mice, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404

Conference paper

Reina-Torres E, Herrnberger L, Sherwood JM, Tamm ER, Overby DRet al., 2015, The Influence of Plasmalemma Vesicle-Associated Protein on Conventional Outflow Facility in Mice, Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404

Conference paper

Stamer WD, Braakman ST, Zhou EH, Ethier CR, Fredberg JJ, Overby DR, Johnson Met al., 2015, Biomechanics of Schlemm's canal endothelium and intraocular pressure reduction, PROGRESS IN RETINAL AND EYE RESEARCH, Vol: 44, Pages: 86-98, ISSN: 1350-9462

Journal article

Braakman ST, Read AT, Chan DW-H, Ethier CR, Overby DRet al., 2015, Colocalization of outflow segmentation and pores along the inner wall of Schlemm's canal, EXPERIMENTAL EYE RESEARCH, Vol: 130, Pages: 87-96, ISSN: 0014-4835

Journal article

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