Biomedical subjects

Paul A Yates

Publications and source records attributed to Paul A Yates.

4 recordsLinked to original sources

PubMed2006

Intravitreal bevacizumab (Avastin) as treatment for subfoveal choroidal neovascularisation secondary to pathological myopia.

OBJECTIVE: To evaluate the safety and efficacy of intravitreal bevacizumab (Avastin) as treatment for subfoveal choroidal neovascularisation (CNV) due to pathological myopia. METHODS: Consecutive series of primary or recurrent subfoveal CNV secondary to myopia treated with intravitreal bevacizumab 1.25 mg between August 2005 and January 2006 at the New England Eye Center, Boston, Massachusetts, USA, were reviewed retrospectively. Data from clinical examination, fundus photography, fluorescein angiography, optical coherence tomography and visual acuity were collected. RESULTS: There were 11 eyes of 9 patients. 5 of 11 eyes had been treated previously with photodynamic therapy. Pre-injection visual acuity measured 20/50 to 20/100 in 6 eyes and 20/200 or worse in 5 eyes. After a mean follow-up of 153 (range 35-224) days, post-injection visual acuity measured 20/20 to 20/40 in 7 eyes, 20/50 to 20/100 in 1 eye and 20/200 or worse in 3 eyes. Three eyes received two bevacizumab injections and eight eyes received one injection. Visual acuity improved by a mean of +3.5 (range -1 to +8 lines) lines, and 8 of 11 eyes achieved 20/50 or better at the last follow-up. Central foveal thickness improved from 340 (range 253-664) microm to 234 (range 142-308) microm, representing an average reduction of 103 (range +4 to -356) microm. No injection complications or drug-related side effects were observed. CONCLUSIONS: In this small series of eyes with limited follow-up, intravitreal bevacizumab seems to be safe and potentially efficacious in eyes with subfoveal CNV secondary to pathological myopia.

Adult↗

PubMed2006

Behçet disease.

Explore the source record for details and available documents.

Behcet Syndrome↗

PubMed2004

Computational modeling of retinotopic map development to define contributions of EphA-ephrinA gradients, axon-axon interactions, and patterned activity.

The topographic projection of retinal ganglion cell (RGC) axons to mouse superior colliculus (SC) or chick optic tectum (OT) is formed in three phases: RGC axons overshoot their termination zone (TZ); they exhibit interstitial branching along the axon that is topographically biased for the correct location of their future TZ; and branches arborize preferentially at the TZ and the initial exuberant projection refines through axon and branch elimination to generate a precise retinotopic map. We present a computational model of map development that demonstrates that the countergradients of EphAs and ephrinAs in retina and the OT/SC and bidirectional repellent signaling between RGC axons and OT/SC cells are sufficient to direct an initial topographic bias in RGC axon branching. Our model also suggests that a proposed repellent action of EphAs/ephrinAs present on RGC branches and arbors added to that of EphAs/ephrinAs expressed by OT/SC cells is required to progressively restrict branching and arborization to topographically correct locations and eliminate axon overshoot. Simulations show that this molecular framework alone can develop considerable topographic order and refinement, including axon elimination, a feature not programmed into the model. Generating a refined map with a condensed TZ as in vivo requires an additional parameter that enhances branch formation along an RGC axon near sites that it has a higher branch density, and resembles an assumed role for patterned neural activity. The same computational model generates the phenotypes reported in ephrinA deficient mice and Isl2-EphA3 knockin mice. This modeling suggests that gradients of counter-repellents can establish a substantial degree of topographic order in the OT/SC, and that repellents present on RGC axon branches and arbors make a substantial contribution to map refinement. However, competitive interactions between RGC axons that enhance the probability of continued local branching are required to generate precise retinotopy.

Animals↗

PubMed2003

Bifunctional action of ephrin-B1 as a repellent and attractant to control bidirectional branch extension in dorsal-ventral retinotopic mapping.

We report that the EphB receptor ligand, ephrin-B1, may act bifunctionally as both a branch repellent and attractant to control the unique mechanisms in mapping the dorsal-ventral (DV) retinal axis along the lateral-medial (LM) axis of the optic tectum. EphB receptors are expressed in a low to high DV gradient by retinal ganglion cells (RGCs), and ephrin-B1 is expressed in a low to high LM gradient in the tectum. RGC axons lack DV ordering along the LM tectal axis, but directionally extend interstitial branches that establish retinotopically ordered arbors. Recent studies show that ephrin-B1 acts as an attractant in DV mapping and in controlling directional branch extension. Modeling indicates that proper DV mapping requires that this attractant activity cooperates with a repellent activity in a gradient that mimics ephrin-B1. We show that ectopic domains of high, graded ephrin-B1 expression created by retroviral transfection repel interstitial branches of RGC axons and redirect their extension along the LM tectal axis, away from their proper termination zones (TZs). In contrast, the primary RGC axons are unaffected and extend through the ectopic domains of ephrin-B1 and arborize at the topographically correct site. However, when the location of a TZ is coincident with ectopic domains of ephrin-B1, the domains appear to inhibit arborization and shape the distribution of arbors. Our findings indicate that ephrin-B1 selectively controls, through either attraction or repulsion, the directional extension and arborization of interstitial branches extended by RGC axons arising from the same DV position: branches that arise from axons positioned lateral to the correct TZ are attracted up the gradient of ephrin-B1 and branches that arise from axons positioned medial to the same TZ are repelled down the ephrin-B1 gradient. Alternatively, EphB receptor signaling may act as a 'ligand-density sensor' and titrate signaling pathways that promote branch extension toward an optimal ephrin-B1 concentration found at the TZ; branches located either medial or lateral to the TZ would encounter a gradient of increasingly favored attachment in the direction of the TZ.

Animals↗