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At least 793 records · Page 44Linked to original sources
PubMed1981

[Early changes in retinal 5'-nucleotidase activity in hereditary retinal degeneration].

Activity of soluble cGMP phosphodiesterase (PDE) and of two membrane enzymes, 5'-nucleotidase and Na,K-ATPase, was studied in the developing retina of rats with inherited retinal degeneration. It was found that by day 10 of life, the content of 5'-nucleotidase in the afflicted rats was significantly reduced as compared with controls. This difference was unchanged throughout the subsequent animals' life. Na,K-ATPase activity in the afflicted and normal animals was the same. Within the first 45 days of life, PDE calculated with respect to the rhodopsin content was not different as regards both the afflicted and normal rats. When calculated with respect to protein, the changes in PDE corresponded with the reported data. The data obtained allowed a suggestion to be made that changes in 5'-nucleotidase in inherited retinal degeneration are disease-specific. They are accounted for by changes in the enzymes of nonphotoreceptor retinal membranes. The changes in PDE may be regarded as secondary, correlating with variation in the number of the photoreceptor membranes.

5'-Nucleotidase↗
PubMed1980

Studies on the retina and the pigment epithelium in hereditary canine ceroid lipofuscinosis. III. Morphologic abnormalities in retinal neurons and retinal pigmented epithelial cells.

Studies of the retina in 6- and 22-month-old English setters with progressive blindness, ataxia, and muscle weakness demonstrated a marked accumulation of abnormal cytosomes within neurons and retinal pigmented epithelial cells. Ganglion cells contained abundant cytosomes with evenly spaced stacks of membranes; bipolar and amacrine cell cytosomes consisted of dense, amorphous material with closely spaced configurations of light and dark lines; cytosomes within photoreceptor cells contained faintly staining curved profiles. All three cytosomes resembled those previously reported in brain neurons of CCL dogs. In retinal pigmented epithelial cells, there were prominent accumulations of lamellar fragments, either free in the cytoplasm or incorporated into melanin granules. These retinal abnormalities are likely to be related to deficiences of peroxidase and defects of lipid peroxidation. The pathologic and biochemical changes seen in these dogs are similar in many respects to those reported in human patients with Batten disease. As such, these dogs provide a convenient model for the study disease mechanisms and for therapeutic approaches to blindness in Batten disease.

Animals↗
PubMed1997

Transthoracic echocardiography in young patients with acute retinal arterial obstruction. RECO Study Group. Retinal Emboli of Cardiac Origin Group.

OBJECTIVE: To report the transthoracic echocardiographic findings in young patients presenting with acute retinal arterial obstruction, given their clinical risk status for cardioembolic disease. DESIGN: Case series. SETTING: Four North American tertiary hospital centres. PATIENTS: Eleven patients less than 45 years of age presenting with acute retinal arterial obstruction who underwent transthoracic echocardiography. OUTCOME MEASURES: Anticoagulation therapy or cardiac surgery. RESULTS: Echocardiography showed abnormalities in five patients (45%). Five of the 11 patients were at high risk for cardioembolic disease on the basis of a history of risk factors or the presence of a cardiac murmur on presentation, or both. Three (60%) of the five had abnormal findings on echocardiography; all three required anticoagulation therapy or cardiac surgery. Of the six patients at low risk two (33%) had abnormal echocardiograms; neither required anticoagulation therapy or surgical intervention. CONCLUSIONS: All the patients who required anticoagulation therapy or cardiac surgery based on the findings on transthoracic echocardiography were deemed to be at high risk for cardioembolic disease. This emphasizes the importance of clinical risk stratification in the systemic evaluation of young patients presenting with acute retinal arterial obstruction.

Acute Disease↗
PubMed1990

Localized retinal detachment with combined central retinal artery and vein occlusion after retrobulbar anesthesia.

The authors report a patient who was observed to have a localized retinal detachment with combined central retinal artery and vein occlusion after cataract surgery performed with retrobulbar anesthesia. The authors propose that this condition resulted from injection of the anesthetic mixture into the optic nerve. No acute neurologic symptoms occurred, but visual loss was severe and permanent. This case adds to the previously reported spectrum of complications from retrobulbar anesthesia.

Adult↗
PubMed1987

Types of avulsed retinal vessels associated with rhegmatogenous retinal detachment: treatment and results.

We performed a prospective study of 87 cases with avulsed retinal vessels in conjunction with tears and rhegmatogenous retinal detachment. The postoperative follow-up period ranged from 6 months to 5 years. The avulsed vessels were classified according to their location (peripheral or central) as well as with respect to their form (5 types). The surgical procedure comprised the fixation of an episcleral sponge implant (high indentation), cryoapplication, and, if necessary, laser coagulation or endodiathermy at a later stage. The postoperative condition of the avulsed vessel mainly depended on its location, the type of avulsion, and the buckle height.

Humans↗
PubMed1987

Retinal neovascularization after branch retinal arterial obstruction.

We examined two eyes from two noninsulin-dependent diabetic patients that developed vitreous hemorrhage secondary to retinal neovascularization after branch retinal arterial obstruction. Although there was no ophthalmoscopic evidence of diabetic retinopathy, diabetes mellitus may have predisposed the retinas to a neovascular response, which was precipitated by the arterial obstruction.

Adult↗
PubMed2005

Effect of arteriovenous sheathotomy on retinal blood flow and macular edema in patients with branch retinal vein occlusion.

PURPOSE: To determine the effect of arteriovenous sheathotomy on retinal blood flow (RBF) in eyes with branch retinal vein occlusion (BRVO). DESIGN: Interventional case series. METHODS: Seven eyes of 7 patients with BRVO underwent sheathotomy and were followed for more than 6 months. RESULTS: At 1 week postoperatively, the RBF in the affected vessels was significantly improved from 14.1 +/- 5.7 to 27.3 +/- 11.3 pixel(2)/sec (P < 0.01), and the foveal thickness (FT) was significantly reduced from 536 +/- 84 to 366 +/- 134 microm (P = 0.03). However, the RBF was reduced again to 11.7 +/- 7.7 pixel(2)/sec at 1 month postoperatively, and the FT was increased to 424 +/- 184 microm. CONCLUSIONS: Arteriovenous sheathotomy led to a transient improvement of the RBF and was effective in reducing macular edema. It is not clear whether the transient effect of sheathotomy affects the long-term visual acuity and macular edema.

Aged↗
PubMedDate not supplied

Retinal neovascularization associated with acute retinal necrosis.

Unilateral acute retinal necrosis (ARN), developed in a previously healthy 17-year-old boy. Neovascularization of the retina and optic disc was observed when the opaque vitreous was removed by pars plana vitrectomy. Following surgery there was a rapid resolution of neovascularization suggesting that intraocular inflammation, rather than retinal ischemia, was the cause of new vessel formation. Analysis of vitreous mononuclear cells with monoclonal antibodies and the fluorescence-activated cell sorter (FACS) revealed mostly T cells; a pattern consistent with intraocular infection as the cause of ARN. The pathogenesis of intraocular infection is complex and some patients with ARN may be helped by systemic immunosuppression (ie, corticosteroids).

Acute Disease↗
PubMed1977

The close interrelationship between increased vascular retinal permeability and blood pressure level. Evidence from retinal fluorangiography.

A long-term study was done by means of interative fluorangiography on microvascular retinal permeability versus the blood pressure control carried out in 11 patients with a diastolic blood pressure of greater than or equal to 130 mm Hg and with retinal exudates, haemorrhages and oedema. No matter what the original disease was (i.e., essential, renovascular, endocrine hypertension or chronic nephropathy with terminal renal failure) the increased permeability appeared to be critically connected with the blood pressure level. Our results confirm that hypertension per se might be the cause of vascular permeability changes.

Adult↗
PubMed1992

[Retinitis caused by cytomegalovirus in patients with AIDS. Clinico-therapeutic aspects and relationship with HIV retinal microangiopathy in a series of 38 patients].

We evaluate retrospectively 38 patients with AIDS and Cytomegalovirus (CMV) retinitis. In 72.5% (45 from 62 eyes) it carried an important sight risk; 50% of the end of the follow-up. Evidence of extraocular illness in 28.5% of the patients. Using control groups the AIDS microvasculopathy is neither more frequent in CMV-retinitis nor associated with a special risk group (p greater than 0.05), we review treatment, follow-up and complications. The median survival was 6 months without significan differences (p greater than 0.05) with or without the finding of microvasculopathy, bilaterality or extraocular illness.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Retinal fold in macula following intraocular gas. An avoidable complication of retinal detachment surgery.

Liquid vitreous was replaced with air during a scleral buckle for a superotemporal retinal detachment. After surgery, the patient was positioned so that air rolled over the detached retina from anterior to posterior, pressing a fishmouthed tear against the buckle that resulted in reattachment. After the air was absorbed, a large retinal fold was seen in the superotemporal macula along the former posterior margin of the detachment. If the patient had been positioned so that air rolled over the detached retina from posterior to anterior, the potentially visually destructive posterior retinal fold could have been avoided.

Absorption↗
PubMed2001

Temporary disruption of the retinal basal lamina and its effect on retinal histogenesis.

An experimental paradigm was devised to remove the retinal basal lamina for defined periods of development: the basal lamina was dissolved by injecting collagenase into the vitreous of embryonic chick eyes, and its regeneration was induced by a chase with mouse laminin-1 and alpha2-macroglobulin. The laminin-1 was essential in reconstituting a new basal lamina and could not be replaced by laminin-2 or collagen IV, whereas the macroglobulin served as a collagenase inhibitor that did not directly contribute to basal lamina regeneration. The regeneration occurred within 6 h after the laminin-1 chase by forming a morphologically complete basal lamina that included all known basal lamina proteins from chick embryos, such as laminin-1, nidogen-1, collagens IV and XVIII, perlecan, and agrin. The temporary absence of the basal lamina had dramatic effects on retinal histogenesis, such as an irreversible retraction of the endfeet of the neuroepithelial cells from the vitreal surface of the retina, the formation of a disorganized ganglion cell layer with an increase in ganglion cells by 30%, and the appearance of multiple retinal ectopias. Finally, basal lamina regeneration was associated with aberrant axons failing to correctly enter the optic nerve. The present data demonstrate that a transient disruption of the basal lamina leads to dramatic and probably irreversible aberrations in the histogenesis in the developing central nervous system.

Agrin↗
PubMed1976

Conduction velocity groupings among axons of cat retinal ganglion cells, and their relationship to retinal topography.

Three unresolved issues in the conduction velocity groupings among the axons of cat retinal ganglion cells have been investigated. These are (i) the degree of separation of the velocity ranges of the axons of X-and W-type ganglion cells; (ii) the question whether the velocities of X-and Y-cell axons (i.e. of t1 and t2 axons have faster velocities than contralaterally projecting axons. Evidence is presented that the velocity ranges of W- and X-cell axons are almost completely separate; that the velocities of X- and Y-cell axons are not graded with retinal eccentricity (except in the immediate vicinity of the area centralis) and that ipsilaterally projecting axons are not faster conducting that contralaterally projecting axons. These results provide a context for summarising present understanding of conduction velocity groupings among the axons of cat retinal ganglion cells.

Animals↗
PubMed1989

The structure of rabbit retinal Müller (glial) cells is adapted to the surrounding retinal layers.

Radial glial (Müller) cells of the rabbit retina were studied by various techniques including Golgi impregnation, scanning electron microscopy, horseradish peroxidase application, and staining of enzymatically isolated cells. This combination of methods produced detailed information on the specialized morphology of the Müller cells within the different topographical regions of the retina, and of the Müller cell processes within the various retinal layers. As a general rule, the retinal periphery contains short thick Müller cells with big endfeet, whereas the thick central retina is occupied by long slender cells with small endfeet. Independent of their location within the retina, Müller cell processes were found to be adapted to the structure of the surrounding retinal layers. Within the outer and inner nuclear layers, Müller cell processes (and somata) extend thin cytoplasmic "bubbles" ensheathing the neuronal somata, as do the "velate" astrocytes in the brain. In the plexiform layers, Müller cells extend many fine side branches between the neuropil, comparable to the protoplasmic astrocytes of the brain. In the thick myelinated nerve fibre layer of the central retina the Müller cell processes are rather smooth, similar to those of fibrous astrocytes. It is concluded that the neuronal microenvironment determines the morphology of a given glial process, or even of a part of a glial process running through a specialized neuronal compartment.

Animals↗
PubMed1992

cFos labeling in rat superior colliculus: activation by normal retinal pathways and pathways from intracranial retinal transplants.

Previous studies in this laboratory have shown that intracranial retinal transplants can establish both anatomical and functional connections with the host brain. Embryonic rat retinae transplanted intracranially into neonatal host brains are capable of evoking appropriate physiological and behavioral responses when illuminated. The present study employs the specific expression of the cFos protein to identify brain regions in which immediate-early gene activation can be recognized in response to flash stimuli delivered to retinal transplants and to normal intact retinae. Stimulation of the intact eye induced significant cFos expression in various visual centers, including the stratum griseum superficiale of the superior colliculus and the pretectal area, but not in the dLGN, suprachiasmatic nucleus, or retina. Animals with functional transplants expressed cFos throughout the depth of the stratum griseum superficiale and stratum opticum of the superior colliculus, thus apparently activating an additional population of superior collicular cells. Like the eye-stimulated animals, animals with functional transplants failed to elicit significant cFos expression in the dLGN or transplanted retina. This study indicates that intracranial retinal transplants are capable of forming functional connections with the host superior colliculus which not only mediate transient changes in electrical activity but also may affect gene expression through the induction of the c-fos gene.

Animals↗
PubMed1988

Rapid, simultaneous determination of isomers of retinal, retinal oxime and retinol by high-performance liquid chromatography.

Thirteen geometric isomers of retinol, retinal and retinal oxime were resolved in a single chromatographic run on two 250 X 4 mm 5-micron LiChrosorb Si 60 columns in series, using 11.2% ethyl acetate, 1.4% 1-octanol and 2% dioxane in hexane as the mobile phase. All the 11-cis and all-trans isomers of retinol and retinal oxime were completely resolved from each other and from the 9-cis and 13-cis isomers. This chromatographic procedure should be particularly useful for quantifying geometric isomers of retinoids in methylene chloride-hydroxylamine extracts of biological samples such as ocular tissues.

Animals↗