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PubMed1999

Organotypic culture system of chicken retina.

Analysis of developmental mechanisms during neuroembryogenesis, evaluation of toxicological effects and testing of neuroprotheses rely to an increasing extent on in vivo-like in vitro models. We have developed a novel organotypic culture system of the chick retina. Tissue slices of embryonic retinae were immobilized on glass coverslips by a fibrin clot and permanently rotated between the gas and medium phase, resulting in regular formation and the maintenance of the retinal cytoarchitecture. Selection of embryonic stage, slice thickness and specimen processing were optimized for culturing. Scanning electron microscopy revealed degradation during increasing culture periods of the fibrin clot, which was used for initial immobilization of explants on glass coverslips. Simultaneously, retinal cells became exposed on the tissue surface. Even after several weeks in vitro, formation and maintenance of plexiform and nuclear layers was evident as revealed by two specific monoclonal antibodies. Immunocytochemistry employing two additional photoreceptor- and radial Müller-antibodies indicated differentiation of neuronal and glial cells specific for the retina. The organotypic culture system promises to facilitate developmental studies of retinal development. Quantitative evaluation of Na(+)-channel blocker mexiletine impact on the histogenesis of retinal explants proved the organotypic culture system to be a valuable tool also for neurotoxicological investigations.

Animals↗
PubMed2005

Developmental expression patterns and localization of DNA-binding protein inhibitor (Id3) in the mouse retina.

Id3 (inhibitor of DNA binding/differentiation), a member of the Id helix-loop-helix protein family, has long been studied as a positive regulator of proliferation and a negative regulator of differentiation. In this study, we examined the expression pattern and cellular phenotypes of Id3 in postnatal and adult mouse retina. Id3 was mainly expressed in the early postnatal inner retina. From the late postnatal development towards adulthood, Id3 expression was confined to the ganglion cell layer and the inner nuclear layer. Colocalization analysis showed that Id3 positive cells were identified as retinal ganglion cells and amacrine cells. The differential expression profiles of Id3 provide the groundwork for the elucidation of its possible role in retinal development.

Age Factors↗
PubMed1993

Risk factors for development of rhegmatogenous retinal detachment in patients with cytomegalovirus retinitis.

We studied 259 patients to determine the time-dependent risk and risk factors for the development of retinal detachment in patients with cytomegalovirus retinitis. The six-month and one-year retinal detachment rates (by eye) were 11% and 24%, respectively. Increasing retinal surface involvement outside of the posterior pole and the presence of retinitis activity were found to be the two covariates that best predicted retinal detachment. Eyes with peripheral involvement greater than 25% had a fivefold risk for detachment, compared to eyes with 10% involvement. If there was retinitis activity and more than 25% peripheral (external to major vascular arcades) involvement, the risk increased to 24-fold. The presence of a fellow eye with retinal detachment was not an independent risk factor. These observations should help in the design of a prophylactic trial intended to prevent retinal detachment and should also help ophthalmologists counsel patients with cytomegalovirus retinitis.

AIDS-Related Opportunistic Infections↗
PubMed2005

Immunocytochemical development of the guinea pig retina.

The aim of the present study was to establish the neurochemical profile of amacrine and horizontal cells during ontogeny in the guinea pig, a precocial species where significant retinal development occurs prenatally as opposed to altricial species where development largely occurs postnatally. The expression of neurochemical markers of horizontal cells and specific amacrine cell populations was investigated from 20 days of gestation (dg, term approximately 67 dg) to adulthood. Amacrine cell populations were identified immunohistochemically using antibodies to gamma-amino-butyric acid, cholineacetyltransferase, calbindin, calretinin, neuronal nitric oxide synthetase and tyrosine hydroxylase; horizontal cells were labelled with calbindin. All markers were present at 30 dg and had attained their mature (adult) laminar distribution and expression by 60 dg. Horizontal cells appeared in their final location at 30 dg with amacrine cell populations appearing in their final locations by 45 dg. Thus, in the guinea pig retina, the amacrine and horizontal cell populations investigated in this study are fully mature prior to birth.

Amacrine Cells↗
PubMed2001

Pattern formation in the zebrafish retina.

During the past 15 years, the zebrafish has become established as a genetic model organism to study vertebrate development. It is particularly well suited for the analysis of the retina, and several genetic screens have yielded a large number of mutants affecting retinal development. Most of these mutants still await thorough analysis and molecular characterization, but work on a handful of genes has already generated interesting results that shed some light on patterning mechanisms employed in the vertebrate retina.

Animals↗
PubMed1996

Influence of a retinal pigment epithelial cell factor(s) on rat retinal progenitor cells.

Retinal development was studied by explant culture of retinas from embryonic and neonatal rats in response to medium conditioned (CM) by a transformed neonatal rat retinal pigment epithelial (tnrRPE) cell line. Retinal explants from embryonic days 16 and 18 and postnatal day 2 Long-Evans rats were cultured for over 3 weeks on a poly-D,L-ornithine-coated surface in RPE-CM only, 10% serum or a serum-free defined medium. By 2 days in vitro, round cells were seen emerging from both embryonic and neonatal retinal explants grown in tnrRPE-CM. With extended time in culture, these round cells had increased in number and were seen in large confluent clusters adjacent to the explants. After 2 weeks in culture, some of these cells had undergone a morphological differentiation as shown by process formation. Insignificant numbers of these same cells were seen in explant cultures grown in 10% serum or serum-free defined medium. When isolated and subcultured, approx. 80% of the round cells from embryonic and neonatal rat retinal explants were densely immunolabeled for opsin and arrestin, both photoreceptor cell markers and neuron-specific enolase, a marker for mature neurons. Cellular retinaldehyde-binding protein, a Müller cell marker, immunolabeled approx. 30% of the cells from embryonic and neonatal rat retinal explants. In addition, nestin, an intermediate filament protein found only in neuroepithelial cells, was present in approx. 70% of the embryonic cells, but in only less than 1% of the neonatal cells. Based on this immunocytochemical characterization, these round cells are termed retinal progenitor cells and because of their mitogenic capacity under these in vitro conditions, these cells appear to possess stem cell characteristics. Moreover, in a 3-day bioassay, tnrRPE-CM caused a twofold and greater increase in harvested progenitor cells from both neonatal and embryonic explants, while cell numbers in control and growth factor-supplemented cultures showed no increase above the initial plating density. In these studies, CM from cultures of transformed neonatal rat RPE cells promoted the production, survival, proliferation and maturation of retinal progenitor cells from neonatal and embryonic rat retinal explants.

Animals↗
PubMed1996

Retinal vein occlusion after trabeculectomy with mitomycin C.

PURPOSE: To evaluate acute retinal vein occlusion as a potential complication of trabeculectomy with mitomycin C in cases of advanced glaucoma. METHODS: The records of three patients who developed retinal vein occlusions immediately after uncomplicated trabeculectomy with mitomycin C were reviewed. RESULTS: All three patients had advanced open-angle glaucoma with total cupping of the optic nerve, severe visual field loss, and evidence of systemic vascular disease. A marked decrease in intraocular pressure was noted in the postoperative period in all of the patients. CONCLUSION: A shift in the lamina cribrosa, associated with the perioperative intraocular pressure change, may have contributed to occlusion of the venous outflow system in these susceptible patients.

Aged↗
PubMed1995

Retinal detachment in AIDS-related cytomegalovirus retinitis.

Patients with acquired immune deficiency syndrome (AIDS) and cytomegalovirus retinitis (CMVR) are surviving longer due to the use of virostatic medicines and improved treatment of opportunistic infections. As a result, retinal detachment is likely to become an increasingly common cause of visual morbidity in these patients. The incidence and outcome of retinal detachment complicating CMVR was studied at two London AIDS centres. Patients with CMVR were identified prospectively and underwent standard treatment. Retinal detachments were diagnosed during regular follow-up. If retinal reattachment surgery was performed, a standard procedure of vitrectomy and silicone oil internal tamponade was employed. Of 147 patients with CMVR, 41 (28%) developed retinal detachments (47 eyes). Forty-three detachments were rhegmatogenous and 4 were exudative. Fifteen eyes of 9 patients with rhegmatogenous detachments underwent retinal reattachment surgery. Of these, visual acuity remained stable or improved in 12 eyes (80%) in the immediate post-operative period. At the last clinic visit, 8 eyes (53%) maintained a visual acuity of 6/60 or better. The visual results of surgery are good in selected patients, bearing in mind the progressive nature of the underlying disease and poor life expectancy.

AIDS-Related Opportunistic Infections↗
PubMed1998

Nutrition supplements and the eye.

PURPOSE: A review of the role of vitamins, minerals, carotenoids and essential fatty acids in relation to eye health. The mode of action may be directly on the eye or by promoting bodily health on which the eye depends. RESULTS: The lens and retina suffer oxidative damage and the anti-oxidant vitamins A, C and E are implicated as protective. Studies in man give indifferent support to the role of nutrition in the development of cataract. In the elderly, vitamin intake may be inadequate, so that a vitamin supplement may be reasonable. Zinc has a role in retinal metabolism and may be beneficial in macular degeneration. Selenium has an anti-oxidant role. Other minerals including copper have a less defined role. Carotenoids are concentrated at the macula and have an anti-oxidant role. A reduced risk of macular degeneration is found in relation to a high serum level. The essential fatty acid, gamma-linolenic acid (GLA), is useful in Sjögren's syndrome and may help in other dry eye conditions. Omega-3 fatty acids are important in retinal development and have a role in preventing cardiovascular disease. CONCLUSION: All persons should be encouraged to maintain healthy nutrition. Middle-aged and elderly patients may benefit from a supplement. An intake in excess of the recommended daily intake may be beneficial, but this is not proven. Further clinical trials are indicated to define the advisability of vitamin, mineral and other supplements. Dosages for recommended intake and for supplements are given.

Carotenoids↗
PubMed1994

Molecular characterization of fish neurolin: a growth-associated cell surface protein and member of the immunoglobulin superfamily in the fish retinotectal system with similarities to chick protein DM-GRASP/SC-1/BEN.

We have used the polymerase chain reaction to isolate cDNAs coding for goldfish and zebrafish neurolin, a previously identified 86 kDa cell surface glycoprotein in the goldfish visual system. Sequence analysis demonstrates that neurolin belongs to the immunoglobulin superfamily and is 51% similar to the chick cell adhesion molecule DM-GRASP, SC-1, BEN. Northern analysis with a riboprobe coding for the C-terminus of neurolin detected two mRNAs of 3.7 kb and 3.3 kb in both embryonic and adult goldfish. Several monoclonal and polyclonal antibodies were generated against immunopurified goldfish neurolin and two are shown to crossreact with zebrafish proteins. Both antibodies identify a zebrafish protein of the same molecular weight as goldfish neurolin on immunoblots. Immunohistochemical studies with these antibodies in the zebrafish retinotectal system demonstrate labeling on young ganglion cells and growing retinal axons in a pattern similar to that found in goldfish. The similarity of neurolin to a known cell adhesion molecule, its expression on developing retinal ganglion cells and axons in both embryos and adult fish, and its re-expression during retinal axon regeneration in the goldfish suggests that neurolin is important during axonal growth in the fish central nervous system.

Activated-Leukocyte Cell Adhesion Molecule↗
PubMed1985

Rapid tightening of blood glucose control leads to transient deterioration of retinopathy in insulin dependent diabetes mellitus: the Oslo study.

In a study of retinopathy during one year of tight blood glucose control 45 type I (insulin dependent) diabetics without proliferative retinopathy were randomised to receive either continuous subcutaneous insulin infusion, multiple insulin injections, or conventional insulin treatment (controls). Near normoglycaemia was achieved with continuous infusion and multiple injections but not with conventional treatment. Blind evaluation of fluorescein angiograms performed three monthly showed progression of retinopathy in the control group, transient deterioration in the continuous infusion group, and no change in the multiple injection group. Half the patients receiving continuous infusion and multiple injections developed retinal cotton wool spots after three to six months. These changes regressed in all but four patients after 12 months. Control patients did not develop cotton wool spots. Patients who developed cotton wool spots are characterised by a larger decrement in glycosylated haemoglobin and blood glucose values, more frequent episodes of hypoglycaemia, a longer duration of diabetes, and more severe retinopathy at onset. A large and rapid fall in blood glucose concentration may promote transient deterioration of diabetic retinopathy.

Adolescent↗
PubMed2005

STAT3 activation in response to growth factors or cytokines participates in retina precursor proliferation.

Growth factors and cytokines play an important role in the development of central nervous systems including neurons of the retina. However, the molecular pathways that trigger cell growth remain unclear in neuronal precursors. In the present studies, we used a retinal explant culture system to investigate the response of signal transducer and activator of transcription factors (STATs) to extrinsic factors during mouse retinal development. Retinas from embryonic and neonatal stages showed that STAT3 but not STAT1 was activated in response to ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), fibroblast growth factor-1 (FGF1), fibroblast growth factor-2 (FGF2), epidermal growth factor (EGF), interferon-alpha (IFN-alpha) and interferon-gamma (IFN-gamma) in distinct patterns. STAT3 activation was detected in the outermost retina layer in response to CNTF, LIF, FGF1, and IFN-alpha 24 hr after stimulation in postnatal day 1 (PN1) explants, but not FGF2, EGF, IFN-gamma, and retinoic acid (RA). Cytokine stimulation increased the number of cells incorporating BrdU and the labelled cells co-localized with phosphorylated STAT3, indicating that STAT3 may play an essential role in coupling extrinsic factors to retina precursor cell (RPC) proliferation. Furthermore, persistent expression of two neural precursor markers, Hes1 and Otx2 was detected in outer retinal layers and correlated with STAT3 activation by CNTF, suggesting that STAT3 activation may play a critical role in stimulating mitotic precursors. These results strongly support a model that STAT3-mediated signalling regulates precursor populations during mouse retina development.

Animals↗
PubMed2000

A screen for dominant modifiers of the irreC-rst cell death phenotype in the developing Drosophila retina.

Programmed cell death (PCD) in the Drosophila retina requires activity of the irregular chiasmC-roughest (irreC-rst) gene. Loss-of-function mutations in irreC-rst block PCD during retinal development and lead to a rough eye phenotype in the adult. To identify genes that interact with irreC-rst and may be involved in PCD, we conducted a genetic screen for dominant enhancers and suppressors of the adult rough eye phenotype. We screened 150,000 mutagenized flies and recovered 170 dominant modifiers that localized primarily to the second and third chromosomes. At least two allelic groups correspond to previously identified death regulators, Delta and dRas1. Examination of retinae from homozygous viable mutants indicated two major phenotypic classes. One class exhibited pleiotropic defects while the other class exhibited defects specific to the cell population that normally undergoes PCD.

Alleles↗
PubMed1993

Distribution of three retinal proteins in developing octopus photoreceptors.

The expression of proteins unique to plasma membrane domains of developing photoreceptors is used as a marker for retinal differentiation in vertebrates. Invertebrate photoreceptors are also compartmentalized, but little information is available on the development of these compartments or the expression of retinal proteins specific to these cellular regions. Using routine electron microscopy techniques, we have made observations on the formation of photoreceptor organelles, including myeloid bodies and rhabdomeres, in embryonic octopus eyes from an early stage in development through hatching. Immunocytochemical experiments on the embryos demonstrate a timed expression of three retinal proteins during development, and the early separation of the octopus photoreceptor plasma membrane into distinct domains. Using polyclonal antibodies for opsin, retinochrome and retinal binding protein we have shown that opsin appears first and is confined to the distal end of the photoreceptor that will eventually differentiate into rhabdomeres. This membrane domain is separated from the proximal/inner segment plasma membrane by a septate junction. Retinochrome is expressed later when the myeloid bodies appear in the inner segments, and retinal binding protein is apparently not synthesized until sometime after hatching. These results suggest that, in the cephalopod retina, protein components of the retinoid cycling apparatus appear in a specific developmental sequence during the differentiation of this tissue.

Animals↗
PubMed2002

Adenosine as a signaling molecule in the retina: biochemical and developmental aspects.

The nucleoside adenosine plays an important role as a neurotransmitter or neuromodulator in the central nervous system, including the retina. In the present paper we review compelling evidence showing that adenosine is a signaling molecule in the developing retina. In the chick retina, adenosine transporters are present since early stages of development before the appearance of adenosine A1 receptors modulating dopamine-dependent adenylate cyclase activity or A2 receptors that directly activate the enzyme. Experiments using retinal cell cultures revealed that adenosine is taken up by specific cell populations that when stimulated by depolarization or neurotransmitters such as dopamine or glutamate, release the nucleoside through calcium-dependent transporter-mediated mechanisms. The presence of adenosine in the extracellular medium and the long-term activation of adenosine receptors is able to regulate the survival of retinal neurons and blocks glutamate excitoxicity. Thus, adenosine besides working as a neurotransmitter or neuromodulator in the mature retina, is considered as an important signaling molecule during retinal development having important functions such as regulation of neuronal survival and differentiation.

Acetylcholine↗
PubMed2005

Development of cholinergic amacrine cells is visual activity-dependent in the postnatal mouse retina.

In the present study, we used immunocytochemistry to study the temporal and spatial arrangement of mouse cholinergic amacrine cells during postnatal retinal development under normal light/dark cycles and during visual deprivation. Choline acetyltransferase (ChAT)-immunolabeled cells were detected in the neuroblastic layer (NBL) and in the ganglion cell layer (GCL) at postnatal day 0 (P0). Between P3-5, two characteristic cholinergic bands were clearly identified in the inner plexiform layer (IPL). The signal intensity of somas and processes progressively increased over the first 2 postnatal weeks. Around eye opening at P12, cholinergic neurons were mature-like. This early developmental process was not altered by visual deprivation. After eye opening, the space between the two cholinergic bands increased continuously and the spatial regularity index changed constantly, indicating that the cholinergic neurons possibly underwent refinement during later postnatal development. The changes occurring following eye opening were retarded by visual deprivation. The morphologies of photoreceptors, horizontal cells, recoverin-positive OFF-cone bipolar cells, rod bipolar cells, dopaminergic amacrine cells, and Müller cells appeared normal. Their stratification in the outer plexiform layer (OPL) and the IPL was not affected by visual deprivation. However, glial cells grew vertically across the entire thickness of dark-reared retinas. Our results suggest that the development of cholinergic neurons before eye opening is independent of the lighting conditions. Their development after eye opening is greatly impeded by visual deprivation. This visual activity-dependent phase of development may be a critical period for the maturation and synaptic wiring of cholinergic amacrine cells in the mammalian retina.

Age Factors↗
PubMed1995

The neuronal intermediate filament, alpha-internexin is transiently expressed in amacrine cells in the developing mouse retina.

We have investigated the expression of intermediate filament proteins in the developing mouse retina by immunohistochemistry. Antibodies against alpha-internexin, the three neurofilament subunits (NF-L, NF-M, NF-H), vimentin, and glial fibrillary acidic protein (GFAP) were used to determine the relative expression of these proteins at different post-natal stages of mouse retinal development. alpha-Internexin is widely distributed in the process of amacrine cells, horizontal cells and retinal ganglion cells before post-natal day 5 (P5). At this age, NF-L and NF-M are detected primarily in the processes of horizontal cells and retinal ganglion cells, but are rarely found in amacrine cell processes. After P5, alpha-internexin is found to colocalize with other neuronal intermediate filaments in the cell processes of horizontal and ganglion cells, but its expression is barely detectable in amacrine cells processes. NF-H is not encountered in either the horizontal cell processes or the ganglion nerve fibers until P5. Vimentin is present in all glial cells (astrocytes and Müller cells) and some horizontal cell processes during development, while GFAP is found only in astrocyte processes of the mature retina. The transient presence of alpha-internexin in amacrine cells only in early development suggests that the protein may play a role in the plasticity of neuronal connections in the retina.

Animals↗