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  • 1
    ISSN: 1573-2622
    Keywords: animal model hereditary retinal degeneration ; clinical electrophysiology ; multifocal ERG ; scanning-laser ophthalmoscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Introduction: Multifocal electroretinography (MF-ERG) is widely used in the detection of local retinal dysfunction. However, the position of the stimulus on the retina and the stability of fixation are usually not directly accessible. Thus, devices have been designed for a continuous fundus visualization during recording. Methods: MF-ERGs were recorded with a RetiScanTM system connected to two different Scanning-laser ophthalmoscopes (SLOs) that use either a red (633 nm) or green (415 nm) laser for stimulation, and a VERISTM 4 system connected to a piggyback stimulator prototype that added the stimulus to the optical pathway of the SLO by means of a wavelength-sensitive mirror. Fundus visualization was achieved with the infrared lasers of the SLOs (780 and 835 nm). Results: The most extensive study so far with a green laser stimulus in a cat model of retinal degeneration demonstrated the capability of the device to detect retinal landmarks and the different stages of degeneration. Also, the advantages of exactly reproducible stimulus positioning for averaging within and comparison between disease groups became apparent. The results with the same setup in transgenic mice suggest a pure cone origin of the responses. In humans, recordings show that fixation is sufficiently good in most subjects. It is not clear yet whether red or green laser stimulation (or both) is preferable. The results with the prototype were very similar to the MF-ERGs obtained with a standard CRT screen. Conclusions: All three devices allowed us to record MF-ERGs with continuous fundus monitoring. Although further refinements are necessary, it is obvious that fundus controlled methods will improve the reliability of MF-ERG in future research on glaucoma, transplantation studies, and evaluation of gene therapy.
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  • 2
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Leber congenital amaurosis (LCA) is the most serious form of the autosomal recessive childhood-onset retinal dystrophies. Mutations in the gene encoding RPE65, a protein vital for regeneration of the visual pigment rhodopsin in the retinal pigment epithelium, account for 10–15% of LCA cases. ...
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  • 3
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Erythropoietin (Epo) is upregulated by hypoxia and provides protection against apoptosis of erythroid progenitors in bone marrow and brain neurons. Here we show in the adult mouse retina that acute hypoxia dose-dependently stimulates expression of Epo, fibroblast growth factor 2 and vascular ...
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  • 4
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Usher syndrome type I (USH1) is an autosomal recessive disorder characterized by congenital sensorineural hearing loss, vestibular dysfunction and visual impairment due to early onset retinitis pigmentosa (RP). So far, six loci (USH1A–USH1F) have been mapped, but only two USH1 genes ...
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  • 5
    ISSN: 1433-0423
    Keywords: Schlüsselwörter Juvenile neuronale Zeroidlipofuszinose ; Klinische Elektrophysiologie ; Speicherkrankheiten ; Netzhautdegeneration ; Key words Juvenile neuronal ceroid lipofuscinosis ; Clinical electrophysiology ; Storage diseases ; Batten's disease ; Retinal degeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Background: Juvenile neuronal ceroid lipofuscinosis (JNCL) is important to the ophthalmologist, since eye symptoms are usually the first evidence of the disease and permit establishment of an early diagnosis. The disorder usually begins with a dramatic loss of vision between age 4 and 10 due to bullseye maculopathy followed by rapid degeneration of the retina and pigment epithelium. Blindness results within 1 to 3 years after onset of symptoms. The further course of the disease is mainly determined by degradation of the CNS with motor and intellectual deficits. Most patients die before the age of 30. Methods: A case of two sisters is presented to demonstrate eye findings and diagnostic procedures, emphasizing electrophysiologic and morphologic tests (peripheral blood smear, histology). Results: Both sisters reported the first decrease in vision at the ages of 8 and 6 respectively; visual acuity at time of visit was light projection (20/400). Both had tapetoretinal degeneration with optic disc atrophy, narrowed vessels, pigment epitheliopathy and bullseye maculopathy. The ERG was almost extinguished in the older sister and greatly reduced in the younger one (scotopic more than photopic). Histologically, vacuolated lymphocytes were found in the peripheral blood smear, as were intracellular inclusions of the fingerprint and curvilinear type in the conjunctival biopsy. Conclusion: During the course of JNCL, it is very common for the vision to be affected at the age of 6 – 7. The correct diagnosis, however, is often made years later when massive neurologic symptoms such as seizures appear. When there is sudden loss of vision in a child of this age combined with a tapetoretinal degeneration, a biopsy or at least a peripheral blood smear should be performed.
    Notes: Hintergrund: Die juvenile neuronale Zeroidlipofuszinose (JNCL) ist für den Augenarzt wichtig, da die Erstsymptome häufig das Auge betreffen und eine frühe Diagnosestellung ermöglichen. Die Erkrankung beginnt im 4. bis 10. Lebensjahr meist mit einem Visusabfall infolge einer Makulopathie, gefolgt von einer rasch fortschreitenden Degeneration von Netzhaut und Pigmentepithel und führt binnen ca. 1 – 3 Jahren zur Erblindung. Danach stehen neurologische Veränderungen (motorische und intellektuelle Defizite) im Vordergrund; der Tod tritt meist bis zur 3. Lebensdekade ein. Methode: Anhand eines Falls von 2 Schwestern werden Befunde und diagnostisches Vorgehen unter Berücksichtigung elektrophysiologischer und ergänzender Untersuchungen (Blutausstrich, Histologie) erläutert. Ergebnisse: Bei der älteren (jüngeren) Schwester traten mit 8(6) Jahren erste Sehprobleme auf; bei der Untersuchung betrug die Sehschärfe Lichtprojektion (0,05). Morphologisch zeigte sich eine tapetoretinale Degeneration mit Papillenatrophie, Gefäßverengung, Pigmentepitheliopathie und Bulls-eye-Makulopathie. Im ERG waren bei der älteren Schwester lediglich Restpotentiale ableitbar, bei der jüngeren war es deutlich vermindert (skotopisch mehr als photopisch). Im Blutausstrich fanden sich vakuolisierte Lymphozyten, bei der histologischen Untersuchung der Bindehautbiopsie zeigten sich Einschlüsse vom Typ der kurvilinearen Körper sowie Fingerprint-Strukturen. Schlußfolgerungen: Trotz einer starken Sehbeeinträchtigung mit bereits ca. 6 – 7 Jahren wird die Diagnose JNCL häufig erst Jahre später, wenn neurologische Symptome wie Grand-mal-Anfälle hinzukommen, gestellt. Bei plötzlichem Visusabfall im entsprechenden Alter und elektrophysiologisch gesicherter tapetoretinaler Degeneration sollten daher zumindest ein peripherer Blutausstrich und ggf. eine Biopsie veranlaßt werden.
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  • 6
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We characterized visual system defects in two recessive zebrafish mutants oval and elipsa. These mutants share the syndromic phenotype of outer retinal dystrophy in conjunction with cystic renal disorder. We tested the function of the larval visual system in a behavioural assay, eliciting optokinetic eye movements by high-contrast motion stimulation while recording eye movements in parallel. Visual stimulation did not elicit eye movements in mutant larvae, while spontaneous eye movements could be observed. The retina proved to be unresponsive to light using electroretinography, indicative of a defect in the outer retina. Histological analysis of mutant retinas revealed progressive degeneration of photoreceptors, initiated in central retinal locations and spreading to more peripheral regions with increasing age. The inner retina remains unaffected by the mutation. Photoreceptors display cell type-specific immunoreactivity prior to apoptotic cell death, arguing for a dystrophic defect. Genomic mapping employing simple sequence-length polymorphisms located both mutations on different regions of zebrafish linkage group 9. These mutants may serve as accessible animal models of human outer retinal dystrophies, including oculo-renal diseases, and show the general usefulness of a behavioural genetic approach to study visual system development in the model vertebrate zebrafish.
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