Distribution of membrane phospholipids in the rabbit neural retina, optic nerve head and optic nerve.

Since diseases of the neural retina and optic nerve can result in alteration of biological membranes, this study determines similarities and differences in the membrane phospholipid content of the neural retina, optic nerve head, and optic nerve to serve as baseline data. Neural retina, optic nerve head, and optic nerve were dissected, isolated as 5 sets from 20 rabbits and frozen in liquid N2. Separate pooled-tissue extracts were prepared for each set of tissues and phosphorus-31 nuclear magnetic resonance (31P NMR) analyses performed. Ten phospholipids were quantified (respective neural retina, optic nerve head, and optic nerve mole % are given for the 5 major phospholipids detected): phosphatidylcholine (PC), 44.61, 27.67, 26.40; PC plasmalogen or alkylacyl PC (CPLIP); phosphatidylinositol (PI); sphingomyelin (SM); phosphatidylserine (PS), 12.63, 14.77, 15.09; phosphatidylethanolamine (PE), 21.21, 9.59, 8.69; PE plasmalogen (EPLAS), 11.07, 30.96, 33.93; an unidentified (unknown) phospholipid (U) at the chemical-shift value of 0.13 ppm; diphosphatidylglycerol (DPG); and phosphatidic acid (PA), 0.46, 2.92, 1.57. Significant differences between the various tissues were determined by the one-way analysis of variance, using a Scheffé range value of P < 0.05. The neural retina in all phospholipids detected except for the uncharacterized (unknown) phospholipid was significantly different from the optic nerve head tissue. The optic nerve head was significantly different from the optic nerve in PC, CPLIP, PE, EPLAS, U, DPG, and PA. The data provide a baseline for studies on pathologically changed neural retina, optic nerve head, and optic nerve.

Distribution of membrane phospholipids in the crystalline lens.

PURPOSE: To determine the phospholipid content of specific anatomic regions within the crystalline lens. METHODS: Phospholipid extracts of tissues dissected from 5 sets of 10 rabbit lenses were analyzed by 31P nuclear magnetic resonance spectroscopy. Twenty-nine pathway-specific metabolic indexes were calculated from groups of phospholipids and ratios of phospholipids. RESULTS: Phospholipid levels (mole percent) were determined from the capsule with attached epithelium, the cortex, and the nucleus. Eleven phospholipids were detected with significant regional differences in the lens phospholipid profiles. The levels of phosphatidylcholine (PC), PC plasmalogen-alkylacyl PC, phosphatidylinositol (PI), phosphatidylethanolamine (PE), and diphosphatidylglycerol (DPG), and of the lyso derivatives (lyso PC and lyso PE) were greater in the capsule plus epithelium than in the cortex or the nucleus. Levels of sphingomyelin, phosphatidylserine, and PE plasmalogen (EPLAS) were less in the capsule plus epithelium than in the cortex or the nucleus. PC, PC plasmalogen-alkylacyl PC, EPLAS, and lyso PE had nearly equal amounts in the cortex and the nucleus. PI, lyso PC, and DPG could not be detected in the nucleus. DPG was only detected in the capsule plus epithelium. An unidentified phospholipid at 0.13 ppm was approximately equal in the cortex and the nucleus, but it could not be detected in the capsule plus epithelium. CONCLUSIONS: These differences demonstrate a significant heterogeneity among these anatomic regions of the lens, and differences in the nucleus relative to other regions studied are consistent with those in membranes that less readily undergo transitions from the relatively impermeable lamellar phase to the more permeable hexagonal HII phase.

Lung cancer, proptosis, and decreased vision.

A 48-year-old man presented to the emergency department with a 3-day history of decreased vision in a painful proptotic right eye. The patient was being treated with chemotherapy and radiation for non-small cell lung carcinoma. Examination showed visual acuity of hand motions, decreased motility, and an afferent pupillary defect on the right, consistent with an orbital apex syndrome. Neuroimaging revealed "dirty" orbital fat and no paranasal sinus disease. Orbital biopsy initially showed only fibrosis; however, on subsequent biopsies, nonseptate hyphae later identified as mucormycosis was recovered. The patient survived with exenteration and systemic amphotericin B.

Acute bilateral ophthalmoplegia in a young woman.

A 34-year-old woman presented with bilateral ophthalmoplegia, ptosis, and mild gait ataxia. Tensilon test, magnetic resonance imaging, and cerebrospinal fluid analysis were normal. She initially denied any alcohol intake but later admitted to significant alcohol and multisubstance abuse. The patient improved dramatically after treatment with thiamine. Wernicke's encephalopathy is discussed, highlighting that it may be present with normal mentation. It should be considered in the differential diagnosis of bilateral ophthalmoplegia even in the absence of altered mental status.