Optic nerve alterations in P27(Kip1) knockout mice.

PURPOSE: To study the morphologic characteristics of the optic nerve (ON) by using an experimental model of knockout mice for the expression of the P27(Kip1) gene, mainly involved in cell cycle arrest, apoptosis control, and retinoblastoma protein phosphorylation. METHODS: Eyeballs with the retrobulbar ON attached were obtained from 26-week-old mice. By using morphologic and morphometric techniques, light and electron transmission microscopy, the ON characteristics were determined in two groups of mice: 1) wild type mice as the control group (n=15), 2) homozygous knockout mice (-/-) for the P27(Kip1) gene as the knockout group (n=15). Glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP) were studied using Western blot and immunoblotting approaches. RESULTS: The ON cross-sectional area was significantly larger in the P27(Kip1) knockout mice group than in the control group (p<0.001). The axon sizes in knockout animals were much larger than in wild-type mice (p<0.001). Higher number of axons forming the ON, intra-axonal degeneration, myelin sheath, and axoplasm density alterations were found in P27(Kip1) knockout mice when compared with control group (p<0.001). Analysis of lysates of optic nerves by Western blot showed less expression of myelin basic protein and GFAP in P27(Kip1) knockout mice as compared to wild type mice (p<0.005, p<0.01, respectively). CONCLUSIONS: The morphologic and morphometric results suggest that homozygous P27(Kip1) knock-out mice had hypertrophic, hyperplastic, and dystrophic ON.

Corneal perforation due to late radiation therapy-induced corneal necrosis--clinicopathological correlation.

A clinicopathological correlation is made between corneal perforation and late radiation therapy-induced corneal necrosis in a male adolescent treated for orbital rhabdomyosarcoma.

Computed tomography and magnetic resonance imaging in the diagnosis of posterior scleritis.

The clinical records of 14 patients with posterior scleritis were reviewed to compare the diagnostic potential of computed tomography (CT) and magnetic resonance imaging (MRI) in this condition. None of these patients had evidence of collagen vascular or other systemic diseases. Done 13 times on 11 patients, CT was diagnostic for posterior scleritis in six patients on seven occasions. We used MRI six times in five patients, and it was not diagnostic for posterior scleritis in any patient. Thus, CT appeared to be more sensitive than MRI in the diagnosis of posterior scleritis. The CT results appeared comparable to ultrasonographic findings (obtained eight times in six patients) in the diagnosis of posterior scleritis. Both CT and MRI, however, detected signs of orbital pseudotumor in six and three patients, respectively. These findings support the concept that posterior scleritis and orbital pseudotumor may represent a continuum of the same disease process.

La isquemia coroidea en la hipertensión arterial maligna / Choroidal ischemia in malignant arterial hypertension

Estudio angiofluoresceíngráfico de 92 pacientes con HTA maligna. En 36 ellos se obsevan imágenes propias de isquemia coroides: retrasos de relleno coroideo, síndromes triangulares, desprendimientos serosos de retina y manchas de Elschnig. Se comentan sus características angiográficas así el mecanismo de producción de las mismas

The SRK regression formula in calculating the dioptric power of intraocular lenses.

One hundred and seventy one eyes with intraocular lenses were studied to compare the predictive accuracy of the Fyodorov and Van der Heijde theoretical formulae of the Sanders-Retzlaff-Kraff (SRK) regression formula. The SRK regression formula was the most accurate. Our personal calculations of the A constants of this formula are given for several types of implants and manufacturers.