Search results for "Retinal"

Pattern Dystrophy of the Macula in a Case of Steinert Disease

2013

<b><i>Introduction:</i></b> Myotonic dystrophies are typically associated with ocular complications like ptosis, weakness of the ocular muscle and cataracts, but also with less recognized retinal changes. <b><i>Case Report:</i></b> A 41-year-old female with type 1 myotonic dystrophy complained of progressive vision loss. Slit lamp examination revealed the presence of typical bilateral polychromatic cataract with posterior subcapsular component. Dilated fundus examination was remarkable for bilateral macular depigmented changes. Multimodal imaging analysis of the macula suggested the presence of a butterfly-shaped pattern dystrophy. <b>&l…

Xanthine oxidase catalyzes the oxidation of retinol.

2007

In mammals, xanthine oxidase (E.C. 1.17.3.2) catalyzes the hydroxylation of a wide variety of heterocyclic substrates such as purines, pyrimidines, and pterins, in addition to aldehydes [1] as all-trans-retinaldehyde [2-5]. Here, we show that buttermilk xanthine oxidase was capable to oxidizing all-trans-retinol (t-ROL) to all-trans-retinaldehyde (t-RAL) that was successively oxidized to all-trans-retinoic acid (t-RA). A rise in the enzyme activity, when t-ROL-CRBP complex was assayed, with respect to the free t-ROL, was observed. Furthermore, treatment of the enzyme with Na2S and glutathione resulted in a significant increment in catalytic activity toward t-ROL and t-RAL, due to the recons…

Xanthine oxidase catalyzes the synthesis of retinoic acid

2001

Milk xanthine oxidase (xanthine: oxygen oxidoreductase; XO; EC 1.1.3.22) was found to catalyze the conversion of retinaldehyde to retinoic acid. The ability of XO to synthesize all trans-retinoic acid efficiently was assessed by its turnover number of 31.56 min-1, determined at pH 7.0 with 1 nM XO and all trans-retinaldehyde varying between 0.05 to 2 microM. The determination of both retinoid and purine content in milk was also considered in order to correlate their concentrations with kinetic parameters of retinaldehyde oxidase activity. The velocity of the reaction was dependent on the isomeric form of the substrate, the all trans- and 9-cis-forms being the preferred substrates rather tha…

Circulating markers of retinal and optic nerve lipids

2013

Purpose Blood lipids are frequently used as a surrogate of lipid composition of peripheral tissues. Even if it is well accepted, such a relationship has never been clearly demonstrated for the eye. The aim of this study was to determine in human samples whether a lipidomic approach based on red blood cells could reveal associations between circulating and ocular lipid profiles. Methods Red blood cells, retinas and optic nerves were collected from 9 human donors. The lipidomic analyses on these tissues were done by both, gas chromatography and liquid chromatography coupled to an electrospray ionization source-mass spectrometer (LC-ESI-MS/MS). Results Gas chromatographic approach did not show…

Statistical atlas based exudate segmentation

2013

International audience; Diabetic macular edema (DME) is characterized by hard exudates. In this article, we propose a novel statistical atlas based method for segmentation of such exudates. Any test fundus image is first warped on the atlas co-ordinate and then a distance map is obtained with the mean atlas image. This leaves behind the candidate lesions. Post-processing schemes are introduced for final segmentation of the exudate. Experiments with the publicly available HEI-MED data-set shows good performance of the method. A lesion localization fraction of 82.5% at 35% of non-lesion localization fraction on the FROC curve is obtained. The method is also compared to few most recent referen…

Role of Oxidative Stress in Aging of the Retina in the ApoB100,LDLR-/- Mouse, a Murine Model of Aging of the Human Retina

2009

Involvement of plasmalogens and iPLA2 in the control of post-natal retinal vascular development in mice

2014

International audience; Purpose: The correct development of retinal blood vessels is essential to ensure vision process through sufficient oxygen and nutrient supplies to the retina. It was shown that polyunsaturated fatty acids (PUFAs) could modulate factors involved in tissue vascularization. A congenital deficiency in ether-phospholipids also termed as "plasmalogens" was shown to lead to abnormal ocular vascularization. Because plasmalogens are considered as reservoirs of PUFAs, we wanted to better understand the mechanisms by which plasmalogens may regulate retinal vascular development through the release of PUFAs by a calcium-independent phospholipase A2 (iPLA2). Methods: Retinal vascu…

Retinal vascular network: description in elderly and pathological process

2020

For more than 10 years, description of the retinal microvascular network has benefited from the development of new imaging techniques. Automatic retinal images analysis software, as well as OCT angiography, are able to highlight subtle and early changes in the retinal vascular network. In addition, these software allow to obtain a large amount of quantitative microvascular parameters which improve the characterization of retinal vascularization. The challenge of current research is to demonstrate the association between these microvascular modifications, systemic vascular aging process and cerebral and cardiovascular disease. Indeed, a physiopathological continuum exists between retinal mic…

Neurophysiologic Testing in Infants With Usher Syndrome Type 1

2009

Purpose: Usher syndrome type 1 needs to be diagnosed at early age, when speech therapy and cochlear implantation can stimulate communication in a deaf child who will confront an additional visual handicap. Molecular diagnosis is not routinely available. Visual function tests are not easily performed in young children. Before the age of six years, progressive retinal degeneration does not always show fundoscopic changes and few data are available regarding neurophysiologic abnormalities. This study was designed to describe electroretinogram (ERG) and visual evoked potentials (VEP) in a series of fourteen children with Usher syndrome type I.Methods: Monocular ERG and binocular VEP were perfor…

Assessment of the toxicity of cholesterol oxides on retinal pigment epithelial cultured cells

2006

International audience; Purpose: Among the retinal lipid deposits found in AMD (age related macular degeneration), esterified and unesterified cholesterol have been identified. Cholesterol that accumulates in Bruch's membrane could be oxidized and lead to cholesterol oxides known as oxysterols. These compounds have cytotoxic activities on many vascular cell types, and we conducted this study to evaluate the cytotoxics effects of oxysterols on retinal pigment epithelial (RPE) cells. Methods: Human RPE cells (ARPE–19) were cultured and treated by 7–ketocholesterol (7–keto), 7–betahydroxycholesterol (7–beta) and 25–hydroxycholesterol (25–OH). ARPE–19 cells viability was determined with MTT ana…