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At least 469 records · Page 26Linked to original sources
PubMed1994

Changes in the retinal pigment epithelium close to retinal vessels in familial adenomatous polyposis.

Congenital hypertrophy of the retinal pigment epithelium (CHRPE) is known to occur in patients with familial adenomatous polyposis. Its relation to the course of the retinal blood vessels is emphasized in this publication. A 15-year-old girl with familial polyposis coli showed a longitudinal strip of whitish change following the course of a superior nasal artery of the left eye, falsely appearing to enclose the blood vessel like a sheath. A 34-year-old woman from another family with polyposis coli also showed a longitudinally orientated area of hypo- and hyperpigmentation close to temporal retinal veins. Two further patients revealed hyperpigmentation of the RPE under retinal vessels. It is hypothesized that these changes indicate an effect of the hypo- and hyperpigmentations of the RPE on the development of retinal vessels. In four patients, multiple dotlike hyperpigmentations were found in the extreme periphery of the retina; however, the bigger patchy hyperpigmentations were predominantly located in the midperiphery of the retina.

Adenomatous Polyposis Coli↗
PubMed1986

Development of traction retinal detachments following intravitreal injections of retinal Muller and pigment epithelial cells.

We injected varying numbers of retinal Muller glia into the rabbit vitreous in an established model of traction retinal detachment. We used indirect ophthalmoscopy to observe the changes elicited during the following 1 month. Although the severity of the tractional changes increased with increasing numbers of the glial cells, the pathology produced stabilized within the 1st week of injury. Muller glia were less effective at eliciting retinal detachments than retinal pigment epithelial cells (RPE) or mixtures of glia and RPE. Intravitreal tissue membranes derived from the glia differed morphologically from those derived from RPE. The glial membranes had fewer fibroblast-like cells, synthesized less extracellular matrix, and showed lower intravitreal cell proliferation, as determined by 3H-thymidine radioautography. Our findings indicate that membranes composed only of Muller glial cells promote less severe retinal pathology than those membranes composed of RPE or mixed cell types.

Animals↗
PubMed2003

Specific isomerization of rhodopsin-bound 11-cis-retinal to all-trans-retinal under thermal denaturation.

The natural ligand of the retinal photoreceptor rhodopsin, 11-cis-retinal, is isomerized to its all-trans configuration as a consequence of light absorption in the first step of the visual phototransduction process. Here we show, by means of difference spectroscopy and high-performance liquid chromatography analysis, that thermal denaturation of rhodopsin induces the same type of isomerization. This effect is likely due to thermally induced conformational rearrangements of amino acid residues in the retinal-binding pocket--possibly implying helical movements--and highlights the tight coupling between 11-cis-retinal and opsin. This effect could have implications in the instability and functional changes seen for certain mutations in rhodopsin associated with retinal disease, and in the stability of the different conformers induced by mutations in other G protein-coupled receptors.

Animals↗
PubMed2001

[A differentiated study of the retinal function in segmental retinitis pigmentosa by multifocal electroretinograms].

PURPOSE: Generalized retinal degenerations such as retinitis pigmentosa may manifest with focal retinal dysfunctions. These may be detected objectively by new electrophysiological techniques, such as multifocal electroretinography (ERG). CASE REPORT: A mother and daughter, aged 81 and 46 years, showed bilateral caudal bone spiculae formations with corresponding cranial visual field defects in the static perimetry of the central visual field (Octopus) and in the kinetic perimetry (Goldmann). RESULTS: Pattern VEP, pattern ERG, EOG, and cone ERG were within the normal range. The scotopic ERG was in the lower normal range. The multifocal cone ERG of the central 50 degrees showed reduced amplitudes and prolonged latencies in the first-order response component. These findings corresponded to the area of the bone spiculae and the scotomata. CONCLUSION: Multifocal ERG enables the detection of focal retinal cone dysfunction in segmental retinitis pigmentosa. It is an additional tool that may aid in the diagnosis and classification of this disease.

Age Factors↗
PubMed2005

Abnormal fundus autofluorescence in relation to retinal function in patients with retinitis pigmentosa.

BACKGROUND: Fundus autofluorescence (AF) in some patients with retinitis pigmentosa is characterized by a parafoveal ring of increased AF which surrounds the centre as hypofluorescent changes appear at the periphery. The aim of this study was to evaluate the AF patterns in relation to retinal function measured by electroretinography and visual fields. METHODS: Thirty-two patients with RP were included in the study. AF imaging of the macular area was performed with the scanning laser ophthalmoscope. Patients were divided in two groups according to their fundus AF patterns. All patients from group 1 had a ring of increased AF of different size but no atrophic areas inside vascular arcades. Patients with a ring of increased AF and round atrophic changes at different eccentricities from their fovea were selected in group 2. Visual fields were tested with kinetic, automated perimetry and microperimetry; the radius of the hyperfluorescent ring and the smallest distance of hypofluorescent areas from the fovea were compared to visual fields, PERG P50 and N95 and mfERG P1 amplitudes of the inner three rings. RESULTS: A linear relationship was found in group 1 between the radius of the ring of increased AF and both the automated (r=0.82) and kinetic perimetry (r=0.80). The radius of the AF ring correlated highly with the PERG P50 (r=0.72) and N95 (r=0.74) amplitudes. In all patients, mfERG responses were reduced at all retinal locations, more pronounced at periphery. There was a good correlation between the ring of increased AF and the P1 amplitude of ring 2 of mfERG (r=0.62). Patients from group 2 had significantly reduced or non-recordable PERGs and mfERGs. The eccentricities of hypofluorescent changes did not correlate with any type of perimetry. CONCLUSIONS: Our results show that in stages of retinitis pigmentosa, before atrophic lesions spread inside the vascular arcades, the pattern of fundus autofluorescence correlates well with functional tests such as perimetry and electroretinography. The ring of increased AF appears to represent the border between functional and dysfunctional retina. This shows that autofluorescence, as a quick and non-invasive imaging tool, may be related to retinal function as well.

Adolescent↗
PubMed1986

Expression of HLA-DR antigen on retinal pigment epithelial cells in retinitis pigmentosa.

Class II (HLA-DR) antigens are cell surface molecules that play a major role in the initiation and perpetuation of immune responses. Although most cells do not constitutively express class II antigens, selected cells can be stimulated to do so in some immunologically mediated disorders. When retinal pigment epithelial cells were evaluated by either immunoperoxidase or immunofluorescent staining of frozen eye sections from normal individuals, HLA-DR antigens were not detected. In contrast, retinal pigment epithelial cells from two patients with retinitis pigmentosa did express HLA-DR antigens. These findings demonstrated that at some time during the course of retinitis pigmentosa, the retinal pigment epithelial cell is activated to express HLA-DR.

Aged↗
PubMed1994

The influences of age, retinal topography, and gender on retinal degeneration in the Fischer 344 rat.

The Fischer 344 (F344) rat is presently the animal of choice for age-related research. The existence of an age-related retinal degeneration was reported previously in the males of this strain, but a gender comparison has not been performed. In this study, histological and morphometric measurements of the retina related to age, retinal topography, and gender were made on 3- to 24-month-old animals. The thicknesses of the outer nuclear layer (ONL) and the photoreceptor layer (PRL) were measured from sagittal sections at six loci. Retinas of both sexes showed steady decline with age in the thicknesses of the ONL and PRL at all locations. An important finding was the presence, after 12 months of age, of a drastically accelerated rate of peripheral retinal degeneration seen only in male subjects. Females showed a less dramatic rate of peripheral degeneration which did not begin until after 18 months of age. In addition, two other forms of retinal degeneration were found--cystoid degeneration was found earlier and more frequently in the male, while a paving-stone type of degeneration was found in both sexes. These two types of lesions were preferentially, but not exclusively found in the peripheral retina. In conclusion, the F344 rat offers a convenient model to study a pattern of retinal degeneration affected by the combination of gender, regional and age-related factors.

Aging↗
PubMed1987

Pupillometric measures of retinal sensitivity in infants and adults with retinitis pigmentosa.

Steady-state pupil diameter was measured in darkness and over a 9 log unit range of Ganzfeld illumination in 20 normal adults, 28 normal infants, 59 adults with retinitis pigmentosa, and 30 children at risk for retinitis pigmentosa. Pupil threshold was defined as the retinal illuminance necessary to decrease pupil diameter by 1.0 mm relative to the diameter in darkness. Spectral measurements in normal adults confirmed that pupil threshold was determined primarily by rods with this procedure. Pupil thresholds of newborns and infants did not differ significantly from those of normal adults. In patients with retinitis pigmentosa, elevations in pupil threshold were related to rod loss as indexed by reductions in rod ERG amplitude. Electroretinographic follow-up of 13 of the children at risk for retinitis pigmentosa showed normal rod ERG function in 5 children who had pupil thresholds within the normal range and significant rod ERG loss in 8 children who had elevated pupil thresholds.

Adolescent↗
PubMed1986

Newborn rat retinal cells transplanted into a retinal lesion site in adult host eyes.

We report the successful grafting of embryonic (newborn) rat retina into a lesion site (die-back zone) of an adult retina with a corresponding 90-100% survival rate. A penetrating lesion was made through the sclera, choroid and retina on the superior surface of the host eye and closed with microsutures. The lesion site was either allowed to stabilize for 5 weeks or immediately received a retinal graft. Retinas were removed from 1-day-old neonate donors, drawn through a small gauge needle and injected into the fresh or stabilized lesion site. Host animals were sacrificed and the eyes processed for light, scanning- and transmission-electron microscopic analysis at 1, 2, and 4 weeks after grafting. Analysis of sections through grafted tissue within the lesion site revealed that the neonatal cells not only survived at all times examined but also continued their development reminiscent of normal littermate controls. Examination of 4-week grafts revealed a laminar pattern similar to adult ganglion cell, inner plexiform, inner nuclear, and outer plexiform layers as well as developing photoreceptor neurons. The grafted tissue could easily be delivered into the retinal lesion site where it established a pattern of retinal layers within the die-back zone. In addition, the plexiform areas of the graft appeared to integrate with those of the host. The age of the adult retina lesion transplantation site had little effect on the graft/host integrative phenomenon. These studies show for the first time a method utilizing immature retinal grafts to fill and/or bridge the wound area of the lesioned adult mammalian retina. These observations also demonstrate the utility of using this model for the study of numerous retinal developmental phenomena.

Animals↗
PubMed2006

Identification of 4-hydroxynonenal-modified retinal proteins induced by photooxidative stress prior to retinal degeneration.

4-Hydroxynonenal (4-HNE) is a reactive aldehyde species generated endogenously from the nonenzymatic oxidation of n-6 polyunsaturated fatty acids under physiological conditions. We have reported that intense white light exposure increases 4-HNE-protein modification in the retina prior to the onset of photoreceptor cell apoptosis. To understand the molecular mechanism(s) underlying the retinal degeneration induced by photooxidative stress, we identified 4-HNE-modified retinal proteins using a proteomic approach. Albino rats were exposed to 5 k lx white fluorescent light for 3 h and retinas were removed 24 h later and pooled. By Western dot blot analysis, the total intensity of 4-HNE-modified proteins was increased 1.5-fold following the exposure compared to dim light controls. In two independent sets of two-dimensional gel electrophoresis/Western blots followed by peptide mass fingerprinting (PMF), nine proteins including voltage-dependent anion channel, enolase 1alpha, aldolase C, crystallins alphaA and betaB3, heterogeneous nuclear ribonucleoprotein A2/B1, albumin, and glutamine synthetase were identified. We observed that 4-HNE modifications of retinal proteins are specific to a particular set of proteins rather than random events on abundant proteins. By immunohistochemistry, localization of 3 identified proteins overlapped with immunoreactivity of 4-HNE-modified proteins in light-exposed retinas. Intense light exposure increases 4-HNE-protein modifications on specific retinal proteins in several functional categories including energy metabolism, glycolysis, chaperone, phototransduction, and RNA processing. Together with previous reports that 4-HNE modification changes protein activities, these results suggest a close association of 4-HNE-protein modifications with the initiation of light-induced retinal degeneration.

Aldehydes↗
PubMed2000

Retinal histopathology of an autopsy eye with advanced retinitis pigmentosa in a family with rhodopsin Glu181Lys.

PURPOSE: To compare histologic findings in an autopsy eye of an 84-year-old man with advanced retinitis pigmentosa and rhodopsin, Glu181Lys, with two cases of autosomal dominant retinitis pigmentosa (one with rhodopsin, Pro23His, and one with rhodopsin, Cys110Arg) and with a normal control, all of comparable age. METHODS: All eyes were prepared for light and electron microscopy within 6 hours after death. RESULTS: Extensive photoreceptor degeneration was revealed in the eyes with retinitis pigmentosa. Some macular cones showed membranous swirls only in the eye with rhodopsin, Glu181Lys. CONCLUSION: The retinal degeneration caused by rhodopsin, Glu181Lys, can feature membranous swirls in the inner segments of cones in the macula. These swirls have not been reported in other cases of dominant retinitis pigmentosa studied so far, and their pathogenesis remains to be defined.

Adult↗
PubMed2002

Transplantation of intact sheets of fetal neural retina with its retinal pigment epithelium in retinitis pigmentosa patients.

PURPOSE: To show the safety of transplanting sheets of fetal neural retina together with its retinal pigment epithelium (RPE) to patients with retinitis pigmentosa. DESIGN: Interventional case series. METHODS: Sheets of fetal neural retina and RPE were transplanted together into the subretinal space near the fovea unilaterally in the eyes of five patients with retinitis pigmentosa who had only light perception in both eyes. The patients were followed for 6 months. The main outcome measures were tissue typing of both donors and recipients, fluorescein angiography, multifocal electroretinogram (mfERG) testing, and clinical examination. No immunosuppressive medications were given. RESULTS: No evidence of rejection was observed. Up to 6 months there was no evidence of tissue disintegration, retinal edema, or scarring. There was no change in vision both by Snellen acuity and with mfERGs. Growth of the transplant was noted in two of five patients at 6 months vs. 2 weeks. All patients typed were HLA mismatched with donor tissue. CONCLUSIONS: This study indicates that fetal retina can be transplanted together with its RPE and survive for at least 6 months without evidence of rejection. However, no improvements in vision were observed, possibly due to the severe retinal degeneration of the patients.

Adult↗
PubMed1985

Clinicopathologic results of vitreous surgery for epiretinal membranes in patients with combined retinal and retinal pigment epithelial hamartomas.

Two patients (a 44-year-old woman and a 26-year-old man) with progressive visual loss associated with macular combined retinal-retinal pigment epithelial hamartomas underwent pars plana vitrectomies with peeling of macular epiretinal membranes. Histopathologic findings for one of the membranes were similar to those in idiopathic or other secondary epiretinal membranes. Although the epiretinal membranes were satisfactorily removed, visual acuity improved in neither eye. Fluorescein angiography showed persistence of vascular tortuosity and leakage and cystoid macular edema after surgery in both cases. One eye developed a late postoperative operculated retinal tear which was successfully treated with cryopexy. The role of vitrectomy and membrane removal in cases of macular combined retinal-retinal pigment epithelial hamartomas appears to be limited.

Adult↗
PubMed1997

Differences in the retinal GABA system among control, spastic mutant and retinal degeneration mutant mice.

Immunocytochemical methods were used to compare the GABA system in control mice and two mutant strains: spastic which has reduced glycine receptors and retinal degeneration mutant in which the photoreceptors degenerate and reportedly have increased GABA and GAD levels. We found that the spastic mutant retina had reduced GABA-immunoreactivity (IR) in the proximal retina, reduced staining for GAD-1440 in the OPL, and reduced GABAA receptor staining in the OPL, compared to control. The retinal degeneration mutant retinas had enhanced GABA-IR throughout the retina, particularly in Müller cells, bipolar cells and IPL, and enhancement of GABAA receptor staining in the OPL, compared to control. The distributions of GABA-IR, GAD-1440-IR and GABAA receptor-IR in retinas of spastic mutant mice that also expressed the retinal degeneration phenotype resembled those found in retinas of mice that expressed only the retinal degeneration phenotype rather than those that expressed only the spastic mutation. No differences were observed among the conditions for GAD-65, GAD-67 or GABA-T. Our results with the spastic and retinal degeneration mutant mice demonstrate that attenuation in the glycinergic system and photoreceptor degeneration, respectively, is accompanied by alterations in different aspects of the GABA system, giving impetus for caution in the interpretation of experiments involving genetic manipulation of complex phenotypes.

Animals↗
PubMedDate not supplied

Long-standing hyperglycemia in C57BL/6J mice does not affect retinal glutathione levels or endothelial/pericyte ratio in retinal capillaries.

Free radicals have been suggested to play a role in the development of diabetic retinopathy. The aim of the present study was to examine whether the metabolic perturbations caused by high-fat feeding of two strains of mice, the C57BL6/J mice and the NMRI mice, interfere with one of the free radical enzyme defense systems in the retina, i. e., glutathione (GSH), and whether morphological changes occur in the retinal vessels. C57BL/6J mice and NMRI mice were fed a high-fat diet (55%) for 18 months. High-fat fed mice of both strains developed overweight, hyperinsulinemia, and hyperlipidemia. In addition, the high-fat fed C57BL/6J mice also developed sustained hyperglycemia for at least 15 months. The C57BL/6J mice had lower retinal GSH levels than the NMRI mice, both when given a normal diet (29.6+/-1.2 vs. 37.1+/-1.4 nmol/mg protein; p<0.01) and when given a high-fat diet (27.0+/-1.6 vs. 34.7+/-2.6 nmol/mg protein; p<0.05). Despite the long-standing hyperglycemia, hyperinsulinemia and hyperlipidemia in the C57BL/6J mice, high-fat feeding did not cause any changes in the retinal tissue levels of GSH (27.0+/-1.6 vs. 29. 6+/-1.2 nmol/mg protein) or cysteine (7.61+/-0.63 vs. 6.80+/-0.59 nmol/mg protein). Similarly, high-fat feeding did not affect retinal GSH or cysteine levels in NMRI mice. No light microscopical retinal vessel changes were seen, either in C57BL/6J or in NMRI mice. The study therefore shows that long-standing metabolic perturbations induced by dietary obesity do not induce signs of retinopathy in two different strains of mice. Further studies are needed to explore whether this is explained by increased expression of protecting systems making these strains of mice resistant to effects of oxidative stress.

Animals↗
PubMedDate not supplied

The effect of retinal growth on the postnatal development and distribution of displaced retinal ganglion cells in the retina of the chameleon (squamata).

Retinal ganglion cells (RGCs) usually increase their dendritic field area with postnatal retinal growth. The mechanisms that regulate the postnatal shape of dendritic arbors in the growing retina are not well understood. Quantitative studies suffer from the difficulty of labeling specific subpopulations of RGCs selectively including their dendritic processes. In this study, we labeled displaced retinal ganglion cells (DGC) that are known to project to the accessory optic system (AOS) in juvenile and adult chameleons by retrograde transport of dextran amines. The complete population of DGCs was quantitatively screened for the effects of postnatal retinal growth on cell morphology, dendritic field coverage, and dendritic arbor size. The adult eye contained 2000 DGCs/retina. This number was already present at birth. The smaller size of the hatchling eye (approximately 1/3 of the adult size) led to higher densities of DGCs. The greatest accumulation of juvenile DGCs (two-fold higher compared to the adult) was found in the periphery of the retina where the greatest surface expansion was observed. DGC dendritic field areas were adjusted proportionally to this expansion in order to maintain a constant dendritic coverage. The increase of dendritic fields was mediated by two putative passive mechanisms: First, an elongation of individual dendrites similar to previous reports of postnatal RGC development in the retina of goldfish and chicks. Second, and more prominent, we observed that neighboring dendrites were pulled apart from each other. This resulted in a looser spacing of the initially tightly packed dendrites of each dendritic arbor. This dispersal of dendrites over a larger area was, due to its passive nature, proportional to the increase of the retinal surface and preserved a constant dendritic coverage irrespective of the animal's age and eye size.

Aging↗
PubMed1999

The structure of retinal dehydrogenase type II at 2.7 A resolution: implications for retinal specificity.

Retinoic acid, a hormonally active form of vitamin A, is produced in vivo in a two step process: retinol is oxidized to retinal and retinal is oxidized to retinoic acid. Retinal dehydrogenase type II (RalDH2) catalyzes this last step in the production of retinoic acid in the early embryo, possibly producing this putative morphogen to initiate pattern formation. The enzyme is also found in the adult animal, where it is expressed in the testis, lung, and brain among other tissues. The crystal structure of retinal dehydrogenase type II cocrystallized with nicotinamide adenine dinucleotide (NAD) has been determined at 2.7 A resolution. The structure was solved by molecular replacement using the crystal structure of a mitochondrial aldehyde dehydrogenase (ALDH2) as a model. Unlike what has been described for the structures of two aldehyde dehydrogenases involved in the metabolism of acetaldehyde, the substrate access channel is not a preformed cavity into which acetaldehyde can readily diffuse. Retinal dehydrogenase appears to utilize a disordered loop in the substrate access channel to discriminate between retinaldehyde and short-chain aldehydes.

Aldehyde Oxidoreductases↗
PubMed1991

Mutations in the human retinal degeneration slow gene in autosomal dominant retinitis pigmentosa.

The murine retinal degeneration slow (rds) gene is a semidominant mutation with a phenotype having rod and cone photoreceptors that develop abnormally and then slowly degenerate. The phenotype is a possible model for retinitis pigmentosa, one of the scores of hereditary human retinal degenerations, which is also characterized by photoreceptor degeneration. We report here three mutations of the human homologue of the rds gene (RDS) that cosegregate with autosomal dominant retinitis pigmentosa in separate families. Our results indicate that some cases of autosomal dominant retinitis pigmentosa are due to mutations at the RDS locus.

Adult↗