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E Vecino

Publications and source records attributed to E Vecino.

At least 19 recordsLinked to original sources
PubMed2005

[Comparison of three methods of inducing chronic elevation of intraocular pressure in the pig (experimental glaucoma)].

PURPOSE: To compare three methods of inducing experimental glaucoma in the adult pig, based on achieving chronic elevation of the intraocular pressure (IOP). METHODS: A total of 16 adult pigs were used in the present study. In all instances, the right eye was used as control and the left eye as the experimental eye. The animals were divided into three groups: 1) 3 pigs in which 3 episcleral veins were cauterized (experimental period = 21 weeks); 2) 6 animals in which the anterior chamber of the eye was injected with a solution containing latex fluorospheres (experimental period = 11 weeks); and 3) 4 pigs in which the anterior chamber of the eye was injected with a solution containing latex fluorospheres plus methylcellulose (experimental period = 11 weeks). RESULTS: The episcleral vein cauterization was the only method which produced a sustained elevation of the IOP throughout most of the experimental period. Moreover, the elevation of the IOP achieved by this method resulted in selective retinal ganglion cell (RGC) loss that affected mainly the mid-peripheral and peripheral retina and caused an increase in the mean soma area of the remaining RGCs. CONCLUSIONS: Cauterization of the episcleral veins resulted in a significant and sustained elevation of the IOP and RGC loss when compared with the other two approaches tested in the present study, which barely modified the pig's RGC distribution. Thus, we conclude that the episcleral vein cauterization is the best of the methods tested to induce experimental glaucoma in the pig.

Animals↗
PubMed2004

Differential expression of calretinin in the developing and regenerating zebrafish visual system.

Calretinin is a calcium-binding protein which participates in a variety of functions including calcium buffering and neuronal protection. It also serves as a developmental marker of retinal ganglion cells (RGCs). In order to study the role of calretinin in the development and regeneration of RGCs, we have studied its pattern of expression in the retina at different developmental stages, as well as during optic nerve regeneration by means of immunohistochemistry. During development, calretinin is found for the first time in RGCs when they connect with the optic tectum. Optic nerves from adult zebrafish were crushed and after different survival times, calretinin expression in the retina, optic nerve tract and optic tectum was studied. From the day of crushing to 10 days later, calretinin expression was found to be downregulated within RGCs and their axons, as was also observed during the early developmental stages of RGCs, when they are not committed to a definite cell phenotype. Moreover, 13 days after lesion, when the regenerating axons arrived at the optic tectum, a recovery of calretinin immunoreactivity within the RGCs was observed. These results indicate that calretinin may play an important role during optic nerve regeneration, Thus, the down-regulation of Calretinin during the growth of the RGC axons towards the target during development as well as during their regeneration after injury, indicates that an increase the availability of cytosolic calcium is integral to axon outgrowth thus recapitulating the pattern observed during development.

Animals↗
PubMed2003

Nonequilibrium dynamics of Andreev states in the Kondo regime.

The transport properties of a quantum dot coupled to superconducting leads are analyzed. It is shown that the quasiparticle current in the Kondo regime is determined by the nonequilibrium dynamics of subgap states (Andreev states) under an applied voltage. The current at low bias is suppressed exponentially for decreasing Kondo temperature in agreement with recent experiments. We also predict novel interference effects due to multiple Landau-Zener transitions between Andreev states.

Journal Article↗
PubMed2003

Role of Müller glia in neuroprotection and regeneration in the retina.

Glial cells are thought to protect neurons from various neurological insults. When there is injury to retina, Müller cells, which are the predominant glial element in the retina, undergo significant morphological, cellular and molecular changes. Some of these changes reflect Müller cell involvement in protecting the retina from further damage. Müller cells express growth factors, neurotransmitter transporters and antioxidant agents that could have an important role in preventing excitotoxic damage to retinal neurons. Moreover, Müller cells contact to endothelial cells to facilitate the neovascularization process during hypoxic conditions. Finally, recent studies have pointed to a role of Müller cells in retina regeneration after damage, dedifferentiating to progenitor cells and then giving rise to different neuronal cell types. In this article we will review the role of Müller glia in neuroprotection and regeneration after damage in the retina.

Animals↗
PubMed2003

[Retinal ganglion cell neuroprotection in culture].

PURPOSE: To study the pig retinal ganglion cell (RGC) survival in culture, analysing the possible neuroprotective effect of retinal Müller glia (RMG) and brain-derived neurotrophic factor (BDNF). METHODS: Adult pig retina were dissociated and cultured under different conditions: 1) on laminin/poly-D-lysine-coated coverslips in chemically defined medium (CDM); 2) on laminin/poly-D-lysine-coated coverslips in CMD supplemented with BDNF; 3) on confluent monolayer cultures of RMG in CDM; 4) on laminin/poly-D-lysine substrate in conditioned medium obtained from RMG. RGCs were identified by immunocytochemistry using antibody against 68 kDa neurofilament and observed under an fluorescent microscope. RGCs were classified on the basis of the size, number and length of neurites, and their survival was assayed for each treatment. RESULTS: Confluent RMG substrates and RMG conditioned medium significantly increased the survival of cultured pig RGC. Moreover these two conditions increased the mean area of RGCs and enhanced neurite growth and elongation. Addition of BDNF to culture medium did not modify survival but increased RGC size, neurite number and neurite length. CONCLUSIONS: These findings demonstrate that factor(s) secreted by RMG exert beneficial effects on adult RGC survival and neurite regeneration in vitro, and might constitute important agent(s) for RGC neuroprotection. BDNF also increases the mean area of RGCs and enhances neurite growth but it does not increase the survival of RGCs.

Animals↗
PubMed2003

[Intracellular pathways leading to apoptosis of retinal cells].

Some ocular diseases, such as retinitis pigmentosa, age-related macular degeneration, glaucoma, retinal detachment, diabetic retinopathy or pathological myopia result in apoptotic death of retinal cells. Caspases are proteases that take part in the intracellular signaling pathways that cause apoptosis in different cell types. By using different experimental models, an increase in caspase activity in retinal cells after damage has been shown. However, some studies have shown that other molecules apart from caspases are activated during apoptosis in the retina. Moreover, the type of caspase that is activated seems to be different depending on the type of retinal cell and the pathology analysed. Inhibition of the processes that result in retinal cell apoptosis could decrease the number of dead cells and prevent the irreversible loss of visual function associated with some pathologies such as glaucoma. In this study we aim to review the basic research studies published in the last years in order to know the molecules and pathways involved in the processes which cause apoptosis of the different types of retinal cells.

Apoptosis↗
PubMed2001

Distribution of the phosphorylated form of microtubule associated protein 1B in the fish visual system during optic nerve regeneration.

Microtubule associated proteins are a heterogeneous group of proteins that have been implicated in regulating microtubule stability. They play an important role in the organisation of the neuronal cytoskeleton during neurite outgrowth, plasticity and regeneration. The fish visual system presents a considerable degree of plasticity. Thus, the retina grows continually throughout life and the optic nerve regenerates after crush. In the present study, we compared the distribution of the microtubule associated protein 1B in its phosphorylated form (MAP1B-phos) in the normal adult fish visual system with that observed during optic nerve regeneration after adult optic nerve crush using a specific monoclonal antibody mAb-150. Expression of MAP1B-phos was observed in some ganglion cell somata and in developing, growing axons within the control optic nerve. Few immunoreactive terminals were seen in the control optic tectum. After optic nerve crush, we found additional MAP1B-phos expression in regenerating axons throughout the visual system. Our results demonstrate that MAP1B-phos is present in growing and regenerating axons of fish retinal ganglion cells, which suggests that the phosphorylated form of MAP1B may play an important role in developmental and regeneration processes within the fish central nervous system.

Animals↗
PubMed2001

[Neurofilaments in neurodegenerative diseases].

Neurofilaments are the most abundant class of intermediate size filaments in adult neurons in central and peripheral nervous system. For a long time, neurofilaments have been thought to be implied in neurodegenerative diseases like lateral amyotrophic sclerosis or infantile spinal muscular atrophy. More recently, it has been observed that retinal ganglion cells containing highest levels of neurofilament protein were the most susceptible to cell death in experimental glaucoma. Currently, it has been shown that usually, in neurodegenerative diseases, a failure in the assembly of neurofilaments and neurofilament accumulation takes place within the soma and axons of motor neurons. However it is not yet clear whether this accumulation is a consequence or main cause of motor neurons dysfunction. Recent use of transgenic animals bearing mutations or alterations in genes coding for neurofilament sub-units or their associated proteins has not solved these questions. These findings, nevertheless have helped to understand the mechanism lying beneath these pathologies.

Animals↗
PubMed1999

NMDA induces BDNF expression in the albino rat retina in vivo.

The effect of an intravitreal injection of NMDA on the expression of brain-derived neurotrophic factor (BDNF) in retinal ganglion cells was investigated in rats. Forty-eight hours after intravitreal injection of NMDA retinal ganglion cell BDNF immunoreactivity was practically obliterated, as was the choline acetyltransferase (ChAT) immunoreactivity associated with a subset of amacrine cells. However, 2h following treatment with NMDA the BDNF immunoreactivity and BDNF mRNA associated with the ganglion cells was enhanced while the amacrine cell ChAT immunoreactivity was clearly reduced and the levels of mRNA coding for rhodopsin and Thy-1 did not change. However, 4h after NMDA injection the increase in BDNF mRNA was now no longer apparent. The results show that synthesis of BDNF is increased in the ganglion cells immediately following an insult by NMDA. It is suggested that this is a natural protective mechanism of rat retinal ganglion cells.

Animals↗
PubMed1999

Neurotrophins and their receptors in the tench retina during optic nerve regeneration.

To understand the role of neurotrophins in the visual system, we investigated the distribution of both neurotrophins and their receptors within the retina of a fish that has the capacity to spontaneously regenerate its optic nerve axons after lesion. Intact retinas and retinas from tench, whose optic nerve had been crushed, were analyzed by immunohistochemistry and in situ hybridization. Trk receptors were mainly immunolocalized in cells of the inner nuclear and ganglion cell layers, a distribution coincident with that of their mRNAs. Nerve growth factor (NGF) immunoreactivity was detected exclusively in Müller cell processes, and brain-derived neurotrophic factor (BDNF) was found in both neuronal bodies and Müller cell processes. Neurotrophin-3 (NT-3) was detected in most of the cell nuclei, and neurotrophin-4/5 (NT-4/5) was localized in fibers and in a few cells in the inner retina. An increase in both TrkA protein and mRNA was detected during axonal regeneration within the retinal ganglion cell layer, reaching a maximum 30 days postcrush and returning to normal levels by day 90, when optic nerve regeneration is almost completed in this fish. None of the other neurotrophins and receptors showed appreciable changes. The heterogeneous distribution patterns of neurotrophins and their receptors in fish retina, their differences from the distribution observed in other species, and the TrkA changes after optic nerve crush suggest an important role for these molecules in the normal physiology of the fish retina and during the regeneration process.

Animals↗
PubMed1998

Increased levels of TrkA in the regenerating retinal ganglion cells of fish.

Retinal ganglion cells of the fish have the spontaneous capacity to regenerate after nerve crush, a phenomenon known to be facilitated by nerve growth factor (NGF). We have studied the high-affinity NGF receptor TrkA, during the regeneration of the tench (Tinca tinca L.) optic nerve, using immunocytochemical techniques. TrkA-like immunoreactivity increased during the regeneration of the retinal ganglion cells. The increase is followed by a change in the subcellular distribution from perinuclear in control cells to cytoplasmic and perinuclear in regenerating ones. This increase was observed when antibodies against the extracellular domain of TrkA were used; no changes in TrkA-like immunoreactivity were observed with antibodies against the intracellular domain of TrkA. We thus conclude that modulation of TrkA is involved in the regeneration of fish retinal ganglion cells.

3T3 Cells↗
PubMed1998

The phosphorylated isoform of microtubule associated protein 1B (MAP1B) is expressed in the visual system of the tench (Tinca tinca, L) during optic nerve regeneration.

By using Western blot analysis and immunohistochemistry we have demonstrated that microtubule associated protein 1B (MAP1B)-phos is present in growing and regenerating axons of retinal ganglion cells of fish (Tinca tinca, L). We have found that the levels of MAP1B-phos substantially increase in regenerating optic nerves. Our observations suggest that MAP1 B-phos plays an important role in regeneration processes in the central nervous system (CNS) of the fish. These results are compared in the present paper with that found in the regenerating peripheral nervous system (PNS) of mammals.

Animals↗
PubMed1998

Spatiotemporal development of the fish retina: distribution of calbindin D-28K.

Using antibodies to the calcium-binding protein calbindin (CB), we have studied the embryonic and postnatal development of retinal cells using the trout as an animal model. Our results reveal that the time course of expression of CB parallels the vitreal to scleral progression of differentiation of the teleost retina. The maturation of the retina also follows a spatial, centro-peripheral gradient of CB-expression with peripheral regions of the more mature retina undergoing maturation processes characteristic of the central retina of younger animals. Moreover, CB-expression within the optic tectum and the further lamination of this centre starts to take place only after the labeled ganglion cell axons arrived at the tectum.

Animals↗
PubMed1998

Immunohistochemical distribution of neurotrophins and their receptors in the rat retina and the effects of ischemia and reperfusion.

1. Neurotrophins are molecules that regulate the survival, development and maintenance of specific functions in different populations of nerve cells. 2. In the present work, we studied the localization, at the cellular level, of the different neurotrophins and their receptors within the rat retina in control and after ischemia-reperfusion of the retina. We found variations in the localization of some of these molecules depending on the reperfusion time of the retina after the ischemic lesion. 3. Thus it is suggested that the changes in the distribution and concentration of neurotrophins and their receptors caused by ischemia are protective reactions related to neuronal damage and synaptic reorganization.

Animals↗
PubMed1998

Diencephalic and mesencephalic structures related to the optic nerve organization in tench (Tinca tinca L., 1758). A study using fluoro-gold.

The location of several diencephalic and mesencephalic structures in the teleost fish, Tinca tinca, which have not been described previously, was made possible by injecting Fluoro-Gold, as an anterograde and retrograde tracer, into the optic nerve. In the pretectal area, we found the tractus opticus accessorius and the nucleus opticus dorsolateralis. We have made some specifications about the location and nomenclature of the branches belonging to the optic tracts and two nuclei also related to the visual system (the nucleus commissura posterior and the nucleus pretectalis periventricularis pars dorsalis). This study also presents the retinal projections to the optic tectum and the glial cells in the injected optic nerve of the tench. The laminar nucleus and Edinger-Westphal nucleus are also identified and described in relation to the ciliary pathway.

Animals↗
PubMed1997

Distribution of S100 immunoreactivity in the retina and optic nerve head of the teleost Tinca tinca L.

The distribution of S100 immunoreactivity within the normal and regenerating retina and optic nerve head of the teleost Tinca tinca L. has been investigated using the avidin-biotin complex (ABC) method and a polyclonal antibody against S100. Astrocytes and Müller cells were labeled with this antibody. This represents the first description of astrocytes localized in the optic nerve head and in the nerve fiber layer of the fish retina displaying a typical bipolar morphology. Horizontal cells in the inner nuclear layer were immunolabeled; we also observed species-specific S100 labeling of horizontal cells of the H1 subtype. No significant changes were seen in the S100 immunoreactive Müller cells, astrocytes, or horizontal cells in the tench retina after optic nerve crushing and during regeneration. These results might help to understand the function of glial cells in the normal and experimentally induced regenerating fish visual system.

Animals↗