Search results for "Retinal"
showing 10 items of 631 documents
Meta-analysis of Genome-Wide Association Studies Identifies Novel Loci Associated With Optic Disc Morphology
2015
Primary open-angle glaucoma is the most common optic neuropathy and an important cause of irreversible blindness worldwide. The optic nerve head or optic disc is divided in two parts: a central cup (without nerve fibers) surrounded by the neuroretinal rim (containing axons of the retinal ganglion cells). The International Glaucoma Genetics Consortium conducted a meta-analysis of genome-wide association studies consisting of 17,248 individuals of European ancestry and 6,841 individuals of Asian ancestry. The outcomes of the genome-wide association studies were disc area and cup area. These specific measurements describe optic nerve morphology in another way than the vertical cup-disc ratio, …
Glutathione-dependent formaldehyde dehydrogenase (ADH3) and low km mitochondrial aldehyde dehydrogenase (ALDH2). New evidence for differential expres…
2011
Epidemiological and experimental studies support the involvement of lipid peroxidation (LPO) in retinal diseases. In addition to other pathogenic mechanisms not fully understood, the possibility remains that peroxidic aldehydes, acting as cytotoxic chemicals, mediate in the progression of chronic ocular disorders.To test proper mechanisms involved in removing peroxidic aldehydes from the retina, in an attempt to understand long-lasting changes induced by LPO, the oxidative and antioxidant enzymatic activities, as well as the retinal distribution and activity of glutathione-dependent formaldehyde dehydrogenase (ADH3) and low km mitochondrial aldehyde dehydrogenase (ALDH2), were studied and c…
Induction of apoptosis in human retinoblastoma cells by topoisomerase inhibitors
1998
PURPOSE:To examine the apoptotic effect induced in human retinoblastoma Y79 cells by camptothecin, etoposide, and amsacrine, to examine the effect of these drugs on the expression of many apoptosis-related modulators, and to test the antiapoptotic effect exerted by insulin-like growth factor-I (IGF-I). METHODS:Morphologic features of apoptosis were demonstrated using acridine orange- ethidium bromide staining and electron microscopy. DNA fragmentation was determined by means of an in situ cell detection procedure (TdT-dUTP terminal nick-end labeling [TUNEL]) or by electrophoresis on agarose gels and was quantified by enzyme-linked immunosorbent assay. The expression of apoptosis-related mod…
Successful subretinal delivery and monitoring of MicroBeads in mice
2013
BACKGROUND: To monitor viability of implanted genetically engineered and microencapsulated human stem cells (MicroBeads) in the mouse eye, and to study the impact of the beads and/or xenogenic cells on retinal integrity. METHODOLOGY/PRINCIPAL FINDINGS: MicroBeads were implanted into the subretinal space of SV126 wild type mice using an ab externo approach. Viability of microencapsulated cells was monitored by noninvasive retinal imaging (Spectralis™ HRA+OCT). Retinal integrity was also assessed with retinal imaging and upon the end of the study by light and electron microscopy. The implanted GFP-marked cells encapsulated in subretinal MicroBeads remained viable over a period of up to 4 mont…
Antioxidant supplementation in diabetic retinopathy
2020
Conventional treatments for diabetic retinopathy (DR) include glycaemic control, laser photocoagulation, vitrectomy, intravitreal triamcinolone, and intravitreal antivascular endothelial growth factor agents. However, these strategies have not been proven capable of halting the progression of this disease in all cases. The mechanisms leading to DR are not fully understood, but there is a growing body of evidence showing that oxidative stress plays a pivotal role in the development of this diabetic complications. Indeed, it has been proposed that oxidative stress is the initial and maintaining event that triggers and provides feedback to the other pathophysiological pathways related to DR. T…
Antioxidant reactions of all-trans retinol in phospholipid bilayers: effect of oxygen partial pressure, radical fluxes, and retinol concentration.
1997
Lipoperoxyl radical-scavenging activity of retinol in unilamellar soybean phosphatidylcholine liposomes was studied under a variety of conditions to appreciate to what extend retinol may be considered an effective antioxidant. Peroxidation, initiated by 2 mM 2,2'-azobis(amidino-propane)hydrochloride (AAPH), was carried out at 160 torr O2 or at 15 torr O2, in the absence or in the presence of 10 to 40 mM retinol. As evaluated by the length of the inhibition periods, t(inh), and by the ratio between the inhibition and propagation rate, R(inh)/R(p), the antioxidant activity of retinol was higher at 15 torr O2 than at 160 torr O2. The consumption rate of retinol was markedly faster at 160 torr …
Neuronal cell cycle: the neuron itself and its circumstances.
2015
Neurons are usually regarded as postmitotic cells that undergo apoptosis in response to cell cycle reactivation. Nevertheless, recent evidence indicates the existence of a defined developmental program that induces DNA replication in specific populations of neurons, which remain in a tetraploid state for the rest of their adult life. Similarly, de novo neuronal tetraploidization has also been described in the adult brain as an early hallmark of neurodegeneration. The aim of this review is to integrate these recent developments in the context of cell cycle regulation and apoptotic cell death in neurons. We conclude that a variety of mechanisms exists in neuronal cells for G1/S and G2/M check…
Binding of 11-cis retinaldehyde to the partially purified cellular retinaldehyde binding protein from bovine retinal pigment epithelium.
1987
11-cis retinaldehyde binding analysis was performed on a bovine retinal pigment epithelium preparation of cellular retinaldehyde binding protein (CRALBP), whose purity degree was estimated as 75%. Equilibrium binding studies were carried out measuring the replacement of tritium-labeled with unlabeled 11-cis retinaldehyde at 25 degrees C. Analysis of the experimental data both by a direct curve-fitting procedure utilizing a non linear least square regression analysis and by a conventional Scatchard plot revealed a single non-interacting binding site with an apparent equilibrium constant of 0.9 X 10(-7) M. A binding stoichiometry of approximately 1 mol of 11-cis retinaldehyde/mol of binding p…
Distal Arthrogryposis type 5 in an Italian family due to an autosomal dominant gain-of-function mutation of the PIEZO2 gene
2022
Abstract Background Arthrogryposis multiplex congenita (AMC) is a group of clinically and etiologically heterogeneous conditions, characterized by prenatal onset contractures affecting two or more joints. Its incidence is about 1 in 3000 live births. AMC may be distinguished into amyoplasia, distal and syndromic arthrogryposis. Distal arthrogryposis (DA) predominantly affects hands and feet. It is currently divided into more than ten subtypes (DA1, DA2A/B, DA3–10), based on clinical manifestations, gene mutations and inheritance pattern. Among them, only a few patients with DA5 have been reported. It is associated to a gain-of-function pathogenic variant of the PIEZO2 gene, encoding for an …
Intraocular Telescopic System Design: Optical and Visual Simulation in a Human Eye Model
2016
Purpose. To design an intraocular telescopic system (ITS) for magnifying retinal image and to simulate its optical and visual performance after implantation in a human eye model. Methods. Design and simulation were carried out with a ray-tracing and optical design software. Two different ITS were designed, and their visual performance was simulated using the Liou-Brennan eye model. The difference between the ITS was their lenses’ placement in the eye model and their powers. Ray tracing in both centered and decentered situations was carried out for both ITS while visual Strehl ratio (VSOTF) was computed using custom-made MATLAB code. Results. The results show that between 0.4 and 0.8 mm of d…