Definition of the unique human extraocular muscle allotype by expression profiling.

The extraocular muscles (EOMs) are a unique group of specialized muscles that are anatomically and physiologically distinct from other skeletal muscles. Perhaps the most striking characteristic of the EOMs is their differential sensitivity to disease. EOMs are spared in Duchenne's muscular dystrophy (DMD) despite widespread involvement of other skeletal muscles. Conversely, they are early and prominent targets in myasthenia gravis and mitochondrial myopathies. It is unclear how EOMs achieve such specialization or a differential response to diseases; however, this has been attributed to a unique, group-specific pattern of gene expression or "allotype." To begin to address these issues as well as define the human EOM allotype, we analyzed the human EOM transcriptome using oligonucleotide-based expression profiling. Three hundred thirty-eight genes were found to be differentially expressed in EOM compared with quadriceps femoris limb muscle, using a twofold cutoff. Functional characterization revealed expression patterns corresponding to known metabolic and structural properties of EOMs such as expression of EOM-specific myosin heavy chain (MYH13) and high neural, vascular, and mitochondrial content, suggesting that the profiling was sensitive and specific. Genes related to myogenesis, stem cells, and apoptosis were detected at high levels in normal human EOMs, suggesting that efficient and continuous regeneration and/or myogenesis may be a mechanism by which the EOMs remain clinically and pathologically spared in diseases such as DMD. Taken together, this study provides insight into how human EOMs achieve their unique structural, metabolic, and pathophysiological properties.

Nitrous oxide anesthesia and intravitreal gastamponade.

The right eye of a 66-year-old man was operated with vitrectomy and peeling of an epiretinal membrane. Perioperatively, the eye was filled with 20% SF6 gas to tamponade retinal breaks. Five days later the patient underwent prostatectomy under general anesthesia using nitrous oxide. Postoperatively the eye had no light perception as a result of ischemic retinopathy. The movement of nitrous oxide into gas-containing spaces in the body has been known for a long time. The use of nitrous oxide in patients with intravitreal gas will elevate the intraocular pressure with risk for closure of the central retinal artery. The present case report highlights the problems that can occur when preoperative assessment is carried out a long time before surgery.

The short-time effect of latanoprost on the intraocular pressure in normal pressure glaucoma.

Latanoprost, a prostaglandin analogue, was given topically to 20 patients with normal pressure glaucoma in a double masked randomized study. Either latanoprost 0.006% or placebo (vehicle) was administered twice a day for 14 days. Latanoprost caused a statistically significant (p < 0.001) reduction in intraocular pressure from a diurnal baseline level of 16.8 to 14.3 mmHg, as measured on day 14. Latanoprost was well tolerated.

Latanoprost administered once daily caused a maintained reduction of intraocular pressure in glaucoma patients treated concomitantly with timolol.

The long term effects of two dose regimens of latanoprost (PhXA41) administered to eyes concomitantly treated with timolol which had not adequately been controlled by timolol alone were compared. A total of 50 patients, 17 with primary open angle glaucoma and 33 with capsular glaucoma, were recruited from five clinics. All had glaucomatous visual field defects and an intraocular pressure (IOP) of at least 22 mm Hg despite treatment with 0.5% timolol twice daily. Patients were randomised to two treatment groups. In one group 0.006% latanoprost was given twice daily, in the other group placebo was given at 8 am and latanoprost at 8 pm for 3 months, with concomitant timolol treatment in both groups. Average daytime IOP (mean (SD)) at baseline (on timolol alone) and after 4 and 12 weeks' treatment was 24.8 (3.6), 16.8 (4.3), and 15.7 (2.4) mm Hg respectively with once daily application of latanoprost and 24.9 (2.9), 18.1 (3.0), and 18.0 (3.6) mm Hg respectively with latanoprost twice daily. No clinically significant side effects were observed during treatment. Latanoprost causes a marked and sustained IOP reduction in eyes which are also being treated with timolol. Latanoprost given once daily is at least as effective and probably superior to a twice daily dose regimen.