Macular spectral-domain optical coherence tomography in patients with X linked retinoschisis.

AIM: To evaluate macular anatomy in patients with X linked retinoschisis (XLRS) using spectral-domain optical coherence tomography (SD-OCT). METHODS: Consecutive observational case series. Clinical features were obtained through retrospective chart review. Only eyes without prior surgical interventions and those scanned with SD-OCT were included. The OCT images were analysed. RESULTS: Fourteen eyes of seven males with XLRS scanned with SD-OCT, age 5 to 45 years, were identified. On clinical examination, stellate spoke-like cystic maculopathy was present in nine eyes, and an atrophic foveal lesion in five eyes. SD-OCT revealed cystoid spaces accounting for retinal splitting in the inner nuclear layer in 12 eyes, and outer plexiform layer in two eyes of one patient. A few small cysts, not accounting for the foveal splitting, were seen in the outer nuclear layer in four eyes and in the ganglion cell layer and/or nerve fibre layer in six eyes. CONCLUSIONS: SD-OCT localised the foveomacular retinoschisis in XLRS to the retinal layers deeper than the nerve fibre layer. In the present study, the foveomacular schisis was seen most frequently in the inner nuclear layer.

Neuronal nicotinic acetylcholine receptor expression by O2A/oligodendrocyte progenitor cells.

Oligodendrocyte precursor cells (O2A/OPC, A2B5(+)) were examined for expression of neuronal nicotinic acetylcholine receptors (nAChR). RT-PCR analysis and immunocytochemistry of O2A/OPCs purified from the rat corpus collusum revealed the expression of nAChR subunits alpha3, alpha4, alpha5, alpha7, beta2, and beta4. Immunoreactivity toward nAChR subunits was not detected in cells induced to differentiate into either oligodendrocytes or astrocytes. Approximately 65% of O2A/OPCs loaded with the calcium-responsive dye FURA-2 increased their intracellular free calcium in response to nicotine application. This response was sensitive to the nAChRalpha4/beta2 antagonist, dihydro-beta-erythroidine (DHbetaE), and the voltage-gated calcium channel antagonist, nifedipine. A subset of nicotine-responsive cells (37%) established DHbetaE or nifedipine-sensitive intracellular free calcium oscillations that continued in the presence of nicotine. Typical oscillations occurred at intervals of 20 to 30 s with progressively diminished amplitudes over a period of 2 to 3 min. In rare cases, oscillations persisted for as long as 10 min. O2A/OPCs exposed to carbachol or AMPA produced no oscillations despite robust increases in intracellular free calcium. The expression of nAChRs in non-neuronal glial precursor cells suggests an expanded role for this receptor system in the development of the mammalian brain. GLIA 33:306-313, 2001. Published 2001 Wiley-Liss, Inc.