Secreted glycoprotein myocilin is a component of the myelin sheath in peripheral nerves.

The structure of the myelin sheath in peripheral nerves requires the expression of a specific set of proteins. In the present study, we report that myocilin, a member of the olfactomedin protein family, is a component of the myelin sheath in peripheral nerves. Myocilin is a secreted glycoprotein that forms multimers and contains a leucine zipper and an olfactomedin domain. Mutations in myocilin are responsible for some forms of glaucoma, a neurodegenerative disease that is characterized by a continuous loss of optic nerve axons. Myocilin mRNA was detected by Northern blotting in RNA from the rat sciatic and ophthalmic nerves. By one- and two-dimensional gel electrophoresis of proteins from the rat and human sciatic nerves, myocilin was found to migrate at an isoelectric point (pI) of 5.2-5.3 and a molecular weight of 55-57 kDa. Immunohistochemistry showed immunoreactivity for myocilin in paranodal terminal loops of the nodes of Ranvier and outer mesaxons and basal/abaxonal regions of the myelin sheath. Double-labeling experiments with antibodies against myelin basic protein showed no overlapping, while overlapping immunoreactivity was observed with antibodies against myelin-associated glycoprotein. The expression of myocilin in the sciatic nerve became detectable at postnatal day (P) 15 and reached adult levels at P20. No or minor expression of myocilin mRNA was found in brain, spinal cord, and optic nerve. mRNA of myocilin was detected in schwannoma cells in situ, but at considerably lower levels than in myelinated nerves. Myocilin might significantly contribute to the structure of the myelin sheath in peripheral nerves.

Transpupillary thermotherapy (TTT) in circumscribed choroidal hemangioma.

BACKGROUND: Choroidal hemangioma presents a therapeutic dilemma. Although it is a benign tumor, it may lead to massive exudation of subretinal fluid and a loss of visual function. Argon laser photo-coagulation in a grid pattern may be followed by initial absorption of subretinal fluid, but recurrence is common. Trans-scleral cryotherapy is difficult to apply at the posterior pole of the eye. External beam irradiation may bear a risk of maculopathy and papillopathy. Brachytherapy does not allow placement of radiation to the hemangioma sparing other retinal or choroidal structures. We sought to determine whether transpupillary thermotherapy (TTT) is suitable for treatment of choroidal hemangioma at the posterior pole. METHODS: We present ten patients with choroidal hemangioma. All of these received TTT. The mean follow-up period was 13.3 months (3-21 months). TTT was delivered via a slitlamp microscope with a diode laser at 810 nm. RESULTS: After TTT, reduction in tumor prominence was observed in eight patients at 3 months after treatment by A scan sonography. Visual acuity improved by more than three lines in four patients, and remained unchanged in all other patients. Two patients were retreated to achieve complete absorption of fluid. Serous retinal detachment persisted in three patients because the hemangioma could not be treated completely because of proximity to the fovea. CONCLUSION: Our preliminary results suggest that TTT may be used effectively to treat some choroidal hemangiomas in the first instance and prevent fluid leakage provided the lesion does not involve the fovea. However, long-term follow-up and more cases are needed to evaluate the long-term visual outcome and potential risks.

Characterization of nitrergic neurons in the porcine and human ciliary nerves.

PURPOSE: To further characterize a subpopulation of choroidal ganglion cells associated with the ciliary nerves. METHODS: Isolated long ciliary nerves of porcine and human eyes containing ciliary nerve-associated ganglion cells (CNGCs) were embedded in Epon for ultrastructural investigation, or wholemounts were stained with antibodies against nitric oxide synthase (NOS), vasoactive intestinal polypeptide (VIP), vesicular acetylcholine transporter, neuropeptide Y (NPY), tyrosine hydroxylase (TH), calcitonin gene-related peptide (CGRP), substance P (SP), and synaptophysin. In addition, wholemount preparations of the choroid and of the anterior segment were stained for reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-D). Serial sections through choroid and anterior segment were stained with the prior antibodies listed. RESULTS: In the porcine choroid only CNGCs were present. They stained for brain (b)NOS and VIP and were surrounded by SP and VIP-immunoreactive (IR) nerve terminals. The axonal processes of the CNGCs followed the ciliary nerves to the anterior eye segment, where they formed a nerve fiber plexus that terminated in the trabecular meshwork. None of the axons passed into the sparse NOS-IR nerve fiber plexus surrounding the choroidal vasculature. The CNGCs in the human choroid morphologically resembled those seen in the pig. CONCLUSIONS: The CNGC proportion of choroidal ganglion cells is presumably involved in the intrinsic (peripheral) innervation of the aqueous outflow tissues and of the choroid.