Search results for "Retinal"

Plasmalogens in the retina: From occurrence in retinal cell membranes to potential involvement in pathophysiology of retinal diseases

2014

Plasmalogens (Pls) represent a specific subclass of glycerophospholipids characterized by the presence of a vinyl-ether bond at the sn-1 position of glycerol. Pls are quantitatively important in membranes of neuronal tissues, including the brain and the retina, where they can represent until almost two-third of ethanolamine glycerophospholipids. They are considered as reservoirs of polyunsaturated fatty acids as several studies have shown that arachidonic and docosahexaenoic acids are preferentially esterified on Pls when compared to other glycerophospholipids. Reduced levels of Pls were observed in a number of neurodegenerative disorders such as glaucoma, the second leading cause of blindn…

Color difference threshold of chromostereopsis induced by flat display emission

2015

The study of chromostereopsis has gained attention in the backdrop of the use of computer displays in daily life. In this context, we analyze the illusory depth sense using planar color images presented on a computer screen. We determine the color difference threshold required to induce an illusory sense of depth psychometrically using a constant stimuli paradigm. Isoluminant stimuli are presented on a computer screen, which stimuli are aligned along the blue–red line in the computer display CIE xyY color space. Stereo disparity is generated by increasing the color difference between the central and surrounding areas of the stimuli with both areas consisting of random dots on a black backgr…

2020

Three distinct types of voltage-dependent K+ channels are expressed by Müller (glial) cells of the rabbit retina.

1994

There is ample evidence that retinal radial glial (Müller) cells play a crucial role in retinal ion homeostasis. Nevertheless, data on the particular types of ion channels mediating this function are very rare and incomplete; this holds especially for mammalian Müller cells. Thus, the whole-cell variation of the patch-clamp technique was used to study voltage-dependent currents in Müller cells from adult rabbit retinae. The membrane of Müller cells was almost exclusively permeable to K+ ions, as no significant currents could be evoked in K(+)-free internal and external solutions, external Ba2+ (1 mM) reversibly blocked most membrane currents, and external Cs+ ions (5 mM) blocked all inward …

Transient reduction of the ocular perfusion pressure and the oscillatory potentials of the ERG

2005

Abstract Purpose. To evaluate the changes of the Oscillatory Potentials (OPs) of Electroretinogram (ERG) caused by short-term hypertension in human subjects, and their relationship with ocular perfusion pressure (OPP). Methods. Suction cup technique in 12 normal volunteers with OPs simultaneously recording. Results. Scotopic and photopic OPs were altered during OPP drop. Scotopic OPs showed more sensitiveness, with higher reduction (from 21% to 47%), when compared to the basal value, than in photopic recordings (from 14% to 34%). In both conditions, the relationship between OPP and OPs presented a steady amplitude before the trough after the +30 step, and rapid recovery after OPP normalisat…

2014

In a subset of inherited retinal degenerations (including cone, cone-rod, and macular dystrophies), cone photoreceptors are more severely affected than rods; ABCA4 mutations are the most common cause of this heterogeneous class of disorders. To identify retinal-disease-associated genes, we performed exome sequencing in 28 individuals with “cone-first” retinal disease and clinical features atypical for ABCA4 retinopathy. We then conducted a gene-based case-control association study with an internal exome data set as the control group. TTLL5, encoding a tubulin glutamylase, was highlighted as the most likely disease-associated gene; 2 of 28 affected subjects harbored presumed loss-of-function…

A homozygous mutation in the TUB gene associated with retinal dystrophy and obesity.

2013

Inherited retinal dystrophies are a major cause of childhood blindness. Here, we describe the identification of a homozygous frameshift mutation (c.1194_1195delAG, p.Arg398Serfs*9) in TUB in a child from a consanguineous UK Caucasian family investigated using autozygosity mapping and whole-exome sequencing. The proband presented with obesity, night blindness, decreased visual acuity, and electrophysiological features of a rod cone dystrophy. The mutation was also found in two of the proband's siblings with retinal dystrophy and resulted in mislocalization of the truncated protein. In contrast to known forms of retinal dystrophy, including those caused by mutations in the tubby-like protein …

Polyglutamine toxicity induces rod photoreceptor division, morphological transformation or death in Spinocerebellar ataxia 7 mouse retina

2010

In neurodegenerative disorders caused by polyglutamine (polyQ) expansion, polyQ toxicity is thought to trigger a linear cascade of successive degenerative events leading to neuronal death. To understand how neurons cope with polyQ toxicity, we studied a Spinocerebellar ataxia 7 (SCA7) mouse which expresses polyQ-expanded ATXN7 only in rod photoreceptors. We show that in response to polyQ toxicity, SCA7 rods go through a range of radically different cell fates, including apoptotic and non-apoptotic cell death, cell migration, morphological transformation into a round cell or, most remarkably, cell division. The temporal profile of retinal remodeling indicates that some degenerative pathways …

Insulin and IGFs induce apoptosis in chick embryo retinas deprived of L-glutamine

1999

In chick embryo retinas, cultured in serum-free medium lacking L-glutamine, IGF-I, IGF-II and insulin induced apoptotic DNA fragmentation and cell death, IGF-I being the most efficacious compound. The apoptotic effect, which was particularly evident in retinas removed from 7-day-old chick embryos, declined with the age of the embryos and disappeared after day 11. Apoptosis appeared after a time lag of 8 h and then increased with time up to 16 h. Cycloheximide, an inhibitor of protein synthesis, was capable of entirely abolishing apoptotic cell death. The effect induced by IGFs or insulin was suppressed by the addition of glutamine. Cytokine-mediated apoptosis was also observed after withdra…

Correlation of Crystallin Expression and RGC Susceptibility in Experimental Glaucoma Rats of Different Ages.

2018

Glaucoma is one of the leading causes of blindness worldwide with age being an important risk factor. However, the pathogenesis remains poorly understood. Aim of this study was to focus on age-dependent molecular changes in an experimental animal model of glaucoma.Intraocular pressure was elevated in Sprague-Dawley rats aged 3, 14, and 47 weeks for a period of 7 weeks by episcleral vein cauterization. Ganglion cell loss was monitored by an immunohistochemical staining of the Brain-specific homeobox/POU (Pit-1, Oct-2, Unc-86) domain protein 3A positive cells in retinal flat-mounts and spectral-domain optical coherence tomography measuring the retinal nerve fiber layer thickness. Molecular pr…