Organic osmolyte and halide permeability pathways activated in epithelial HeLa cells by cell swelling were studied by radiotracer efflux techniques and single-cell volume measurements. The replacement of extracellular Cl− by anions that are more permeant through the volume-activated Cl− channel, as indicated by electrophysiological measurements, significantly decreased taurine efflux. In the presence of less-permeant anions, an increase in taurine efflux was observed. Simultaneous measurement of the125I, used as a tracer for Cl−, and [3H]taurine efflux showed that the time courses for the two effluxes differed. In Cl−-rich medium the increase in I− efflux was transient, whereas that for taurine was sustained. Osmosensitive Cl− conductance, assessed by measuring changes in cell volume, increased rapidly after hypotonic shock. The influx of taurine was able to counteract Cl− conductance-dependent cell shrinkage but only ∼4 min after triggering cell swelling. This taurine-induced effect was blocked by DIDS. Differences in anion sensitivity, the time course of activation, and sensitivity to DIDS suggest that the main cell swelling-activated permeability pathways for taurine and Cl− are separate.
Candida endophthalmitis is associated with a high rate of visual loss, particularly in patients with poor presenting visual acuity or centrally located lesions. Early vitrectomy reduces the risk of retinal detachment.
Intravitreal triamcinolone acetonide appears to be an effective supplementary tool in the management of CME refractory to systemic immunosuppressive therapy. Retreatment might be required in some and may be associated with elevated intraocular pressure and cataract.
Purpose
To report a case of autosomal dominant dyskeratosis congenita (AD-DC) complicated by bilateral retinal vasculopathy and proliferative retinopathy with vitreous hemorrhage in the right eye, in the absence of pancytopenia.
Methods
We report a 32-year-old woman who presented with floaters in her right eye. She underwent complete ophthalmic examination and fundus fluorescein angiography.
Results
Funduscopic examination revealed vascular sheathing in the temporal periphery of both eyes and a vitreous hemorrhage in the right eye. Fluorescein angiography showed retinal neovascularization in the right eye and bilateral temporal peripheral capillary nonperfusion. Treatment consisted of laser photocoagulation directed to the areas of capillary nonperfusion in both eyes. A point mutation in the TERC gene confirmed the diagnosis of AD-DC.
Conclusions
Autosomal dominant dyskeratosis congenita is a rare form of inherited bone marrow failure and its presentation is milder than seen in patients with X-linked and autosomal recessive mutations. These patients may lack the classic clinical triad, so it is important to have a high index of suspicion and to be aware of retinal vasculopathy as a complication of dyskeratosis congenita as it may severely compromise vision. Appropriate treatment includes prompt laser photocoagulation to areas of retinal nonperfusion.
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