Effects of intraocular irrigation with melphalan on rabbit retinas during vitrectomy.

PURPOSE: To investigate the toxic effects of perfusion of intravitreal melphalan during vitrectomy on the rabbit retina. METHODS: We performed electoretinography (ERG) in 18 eyes of 18 healthy albino rabbits before and after intraocular melphalan perfusion at concentrations of 5-, 10-, and 20-microg/ml during pars plana vitrectomy. Fellow eyes that underwent vitrectomy without melphalan served as controls. The histopathologic retinal changes were observed in both eyes of two rabbits from each group. RESULTS: In the 5-microg/ml perfusion group, the ERGs and histology showed no substantial changes compared with control fellow eyes during 28 days postoperatively. In the 10- and 20-microg/ml groups, the mean a-wave amplitude decreased to 52% and 31% respectively of the fellow eye; the mean b-wave amplitude decreased to 52% and 19% respectively. However, the peak implicit time of the a- and b-waves did not significantly differ in the 10- and 20-microg/ml groups during 28 days postoperatively. Histologic sections showed necrosis of the inner nuclear layer and thinning of the outer nuclear layer in the 10-microg/ml group. Loss of the outer nuclear layer and the photoreceptor layer and necrosis of the inner nuclear layer were observed in the 20-microg/ml group. CONCLUSION: The intravitreal 5-microg/ml melphalan perfusion during vitrectomy appears to be nontoxic to the retina. This therapeutic modality might be a potential treatment for retinoblastoma with vitreous seeding.

Triamcinolone acetonide suppresses interleukin-1 beta-mediated increase in vascular endothelial growth factor expression in cultured rat Müller cells.

PURPOSE: Intravitreal injection of triamcinolone acetonide (TA) is used for the treatment of diabetic macular edema and other vitreoretinal diseases. Vascular endothelial growth factor (VEGF) plays a key role in regulating vascular permeability associated with macular edema. We investigated the effect of TA on the expression of VEGF mRNA and protein induced by interleukin-1 beta (IL-1b) and hypoxia in cultured rat Müller cells. METHODS: Müller cells were isolated from removed eyeballs of 40 rats. Total RNA was prepared from Müller cells stimulated by IL-1b or hypoxia, in the absence or presence of TA, and then was subjected to Northern blot analyses. The amount of VEGF protein in the culture medium was measured by enzyme-linked immunosorbent assay (ELISA). The stability of RNA was determined by actinomycin D decay assay. Reporter construct, consisting of the VEGF promoter-luciferase gene, was transiently transfected into Müller cells for luciferase assays. RESULTS: Stimulation of Müller cells by either IL-1b or hypoxia induced VEGF mRNA expression. Pretreatment of cells with TA efficiently suppressed VEGF induction by IL-1b but not by hypoxia. ELISA showed that TA significantly reduced the production of VEGF protein from IL-1b-stimulated cells. RNA decay assays and promoter analysis of the VEGF gene indicated that TA inhibited the IL-1b-mediated increase in VEGF gene expression at the transcriptional level. CONCLUSIONS: TA suppressed VEGF expression induced by IL-1b in Müller cells at the transcriptional level. Our data sustained the clinical effect of TA for diabetic macular edema and suggested an important role of TA for the suppression of the VEGF gene expression in ocular tissues.

Correlation of optical coherence tomography with angiography in retinal pigment epithelial detachment associated with age-related macular degeneration.

PURPOSE: To correlate optical coherence tomography (OCT) with angiographic signs of choroidal neovascularization (CNV) in retinal pigment epithelial detachment (PED) associated with age-related macular degeneration (ARMD). METHODS: Prospectively, the authors performed OCT in 35 eyes of 35 patients (30 men and 5 women with a mean age of 71.6 years [range, 56-76 years]) with ARMD. All 35 eyes had CNV in the area of PED or adjacent to it, which was shown by fluorescein or indocyanine green angiography. Cross-sectional images were obtained by the OCT scanning line through the CNV and PED. RESULTS: In 10 (56%) of 18 eyes in which the CNV was at the margin of the PED, a small PED was adjacent to the central, dome-shaped PED. There was a notch between the central and small mounds of PED. In 13 (76%) of 17 eyes in which the CNV was within the PED, a notch was seen in the dome-shaped PED, resulting in a contour with 2 mounds. One of the 2 mounds contained a highly reflective mass immediately beneath the detached retinal pigment epithelium in 8 (62%) of the 13 eyes. CONCLUSION: A tomographic notch in the PED may be diagnostically important as an indication of CNV beneath the detached retinal pigment epithelium in eyes with ARMD.

Predominant expression of GluR2 among the AMPA receptor subunits in neuronal progenitor cells of the rat hippocampus.

Cells derived from the hippocampus of embryonic day 18 (E18) rats were cultured in B27-supplemented Neurobasal medium without serum. We found the presence of numerous small cells with round or elliptical somata and fine processes in this primary culture. These cells were first detectable on culture day 8 and gradually increased in number that reached the maximum on approximately day 14. They incorporated bromodeoxyuridine (BrdU) and expressed nestin, a marker of stem cells and progenitor cells. Furthermore, nearly a half of these cells also expressed neuron-specific beta tubulin. On the other hand, they did not express O4 and glial fibrillary acid protein (GFAP), markers of oligodendrocytes and astrocytes, respectively. Thus, these small cells are most likely to be neuronal progenitor cells. The whole-cell patch clamp studies revealed that these cells expressed voltage-gated Na+, Ca2+ and K+ channels. With regard to ligand-gated channels, these cells were sensitive to alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA), but not to N-methyl-D-aspartate (NMDA). The current-voltage relationship of the AMPA-induced current was slightly outwardly rectifying, suggesting that the AMPA receptors contained the GluR2 subunit in their oligomeric assemblies. The single-cell reverse transcription (RT)-PCR analysis revealed that GluR2 is predominant over the other AMPA receptor subunits in these cells. Furthermore, GluR2 was expressed mainly in the flip form.

Blockage of Ca(2+)-permeable AMPA receptors suppresses migration and induces apoptosis in human glioblastoma cells.

Glioblastoma multiforme is the most undifferentiated type of brain tumor, and its prognosis is extremely poor. Glioblastoma cells exhibit highly migratory and invasive behavior, which makes surgical intervention unsuccessful. Here, we showed that glioblastoma cells express Ca(2+)-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)-type glutamate receptors assembled from the GluR1 and/or GluR4 subunits, and that their conversion to Ca(2+)-impermeable receptors by adenovirus-mediated transfer of the GluR2 cDNA inhibited cell locomotion and induced apoptosis. In contrast, overexpression of Ca(2+)-permeable AMPA receptors facilitated migration and proliferation of the tumor cells. These findings indicate that Ca(2+)-permeable AMPA receptors have crucial roles in growth of glioblastoma. Blockage of these Ca(2+)-permeable receptors may be a useful therapeutic strategy for the prevention of glioblastoma invasion.

Persistent foveal retinal detachment after successful rhegmatogenous retinal detachment surgery.

PURPOSE: To describe the tomographic features of the neurosensory retina after successful rhegmatogenous retinal detachment surgery. DESIGN: Cohort study. METHODS: We prospectively examined cross-sectional retinal images using optical coherence tomography (OCT) in 15 eyes of 15 consecutive patients (mean age, 46 years) who underwent scleral buckling surgery for treatment of rhegmatogenous retinal detachment. The retinas appeared reattached upon binocular stereoscopic indirect ophthalmoscopy. All eyes were examined at 1, 3, 6, and 12 months postoperatively. The time from onset of subjective symptoms of retinal detachment to retinal surgery ranged from 4 to 66 days (mean, 14 days). The postoperative OCT findings and best-corrected visual acuity were statistically analyzed using the Mann-Whitney U test. RESULTS: The detached retinas appeared attached on ophthalmoscopy in all eyes 1 month postoperatively. OCT showed residual retinal detachment in four eyes (27%) at the fovea and in three eyes (20%) at the fovea and adjacent area. The remaining eight retinas (53%) were attached when examined tomographically. In six of the seven eyes with residual foveal detachment by OCT, the retinas reattached spontaneously up to 12 months postoperatively. The postoperative best-corrected visual acuity improved gradually during 12 postoperative months in all 15 eyes. A substantial increase in visual acuity occurred when the fovea reattached in the six eyes with residual detachment. CONCLUSIONS: Foveal retinal detachment may persist after successful retinal detachment surgery in eyes in which the fovea appeared to be attached on ophthalmoscopy. The residual foveal detachment may explain, in part, the delayed visual acuity improvement after successful scleral buckling.