Evaluation of the neuroprotective efficacy of the gramine derivative ITH12657 against NMDA-induced excitotoxicity in the rat retina.

Purpose: The aim of this study was to investigate, the neuroprotective effects of a new Gramine derivative named: ITH12657, in a model of retinal excitotoxicity induced by intravitreal injection of NMDA. Methods: Adult Sprague Dawley rats received an intravitreal injection of 100 mM NMDA in their left eye and were treated daily with subcutaneous injections of ITH12657 or vehicle. The best dose-response, therapeutic window study, and optimal treatment duration of ITH12657 were studied. Based on the best survival of Brn3a + RGCs obtained from the above-mentioned studies, the protective effects of ITH12657 were studied in vivo (retinal thickness and full-field Electroretinography), and ex vivo by quantifying the surviving population of Brn3a + RGCs, αRGCs and their subtypes α-ONsRGCs, α-ONtRGCs, and α-OFFRGCs. Results: Administration of 10 mg/kg ITH12657, starting 12 h before NMDA injection and dispensed for 3 days, resulted in the best significant protection of Brn3a + RGCs against NMDA-induced excitotoxicity. In vivo, ITH12657-treated rats showed significant preservation of retinal thickness and functional protection against NMDA-induced retinal excitotoxicity. Ex vivo results showed that ITH12657 afforded a significant protection against NMDA-induced excitotoxicity for the populations of Brn3a + RGC, αRGC, and αONs-RGC, but not for the population of αOFF-RGC, while the population of α-ONtRGC was fully resistant to NMDA-induced excitotoxicity. Conclusion: Subcutaneous administration of ITH12657 at 10 mg/kg, initiated 12 h before NMDA-induced retinal injury and continued for 3 days, resulted in the best protection of Brn3a + RGCs, αRGC, and αONs-RGC against excitotoxicity-induced RGC death. The population of αOFF-RGCs was extremely sensitive while α-ONtRGCs were fully resistant to NMDA-induced excitotoxicity.

Dexamethasone PLGA Microspheres for Sub-Tenon Administration: Influence of Sterilization and Tolerance Studies.

Many diseases affecting the posterior segment of the eye require repeated intravitreal injections with corticosteroids in chronic treatments. The periocular administration is a less invasive route attracting considerable attention for long-term therapies. In the present work, dexamethasone-loaded poly(lactic-co-glycolic) acid (PLGA) microspheres (Dx-MS) were prepared using the oil-in-water (O/W) emulsion solvent evaporation technique. MS were characterized in terms of mean particle size and particle size distribution, external morphology, polymer integrity, drug content, and in vitro release profiles. MS were sterilized by gamma irradiation (25 kGy), and dexamethasone release profiles from sterilized and non-sterilized microspheres were compared by means of the similarity factor (f2). The mechanism of drug release before and after irradiation exposure of Dx-MS was identified using appropriate mathematical models. Dexamethasone release was sustained in vitro for 9 weeks. The evaluation of the in vivo tolerance was carried out in rabbit eyes, which received a sub-Tenon injection of 5 mg of sterilized Dx-MS (20-53 µm size containing 165.6 ± 3.6 µg Dx/mg MS) equivalent to 828 µg of Dx. No detectable increase in intraocular pressure was reported, and clinical and histological analysis of the ocular tissues showed no adverse events up to 6 weeks after the administration. According to the data presented in this work, the sub-Tenon administration of Dx-MS could be a promising alternative to successive intravitreal injections for the treatment of chronic diseases of the back of the eye.

Analysis of Lymphotoxin Alpha Expression in Human Retina and Generation of Expression Vectors to Functional Characterization of Polymorphisms in the Tumor Necrosis Factor Locus.

With the evolution of new genomic sequencing technologies an important amount of genomic data has been provided. As a consequence of this, many gene polymorphisms have been shown to be significantly associated with different disorders. Many strategies have been implemented to reveal the role of having more than one allele at a specific locus and their involvement in the illnesses. Site-directed mutagenesis is one of the most common strategies to understand the regulatory regions of genes and the relationship between the protein structure and its function. Here, we describe the analysis of lymphotoxin alpha expression in human retina and the generation of expression vectors to functional characterization of polymorphisms in the tumor necrosis factor locus using pCEFL-Flag expression vector and transfection assays in COS-1 cell line.

Immunohistochemical assay for neuron-specific enolase, synaptophysin, and RB-associated protein as a diagnostic aid in advanced retinoblastomas.

PURPOSE: We evaluated the expression of the neural markers, neuron-specific enolase, and synaptophysin, as a tool to confirm the diagnosis of retinoblastoma (RB) in undifferentiated and advanced tumors. Additionally, we determined whether the extent of RB-associated protein (pRb) expression is helpful in assessing the prognosis in RB patients. METHODS: Conventional whole tissue section and tissue microarray immunohistochemistry for neuron-specific enolase, synaptophysin, and pRb were carried out in a series of 22 RBs. RESULTS: Neuron-specific enolase and synaptophysin were expressed in 75%-100% of the tumor cells, and the staining intensity was strong. Two RBs expressed pRb in 75%-100% of the tumor cells, also with strong staining intensity. Concordance between the immunohistochemical outcomes for whole tissue staining and tissue microarray staining was 76.2% for neuron-specific enolase, 85.7% for synaptophysin, and 80.0% for pRb. CONCLUSION: Neuron-specific enolase and synaptophysin have the potential to be useful markers for the diagnosis of RBs. Extensive and strong pRb staining is not associated with less aggressive tumor behavior according to the pathologic classification of RBs.

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Lipophilic substances in intraocular silicone oil.

PURPOSE: To examine intravitreal silicone oil samples for lipophilic substances, including cholesterol, fatty acids, and derived methyl esters. DESIGN: Clinical interventional case series study. METHODS: The study included 53 patients (53 eyes; mean age 57.6 years) who underwent removal of intravitreal silicone oil used for intraocular tamponade with pars plana vitrectomy for retinal detachment. The silicone oil was removed 8.3 +/- 5.7 months after pars plana vitrectomy and analyzed using gas chromatography with a flame ionization detector. RESULTS: Cholesterol was present in all samples with a mean concentration of 65 +/- 32.3 microg/ml (95% confidence interval: 56.1 to 73.9 microg/ml). The concentration increased (P < .001) with the time of tamponade, and decreased (P = .003) with the age of the patients. Fatty acids along with derived methyl acids were detected in low concentrations in 49 samples (92.5%). CONCLUSIONS: Cholesterol and lipophilic acids accumulate in intravitreal silicone oil used in intraocular tamponade.

Cytokine gene polymorphisms in retinal detachment patients with and without proliferative vitreoretinopathy: a preliminary study.

PURPOSE: Cytokines and other growth factors such as interleukins play an important role in the pathogenesis of proliferative vitreoretinopathy (PVR). Interindividual variations in cytokine production seem to correlate with some cytokine gene polymorphisms. The purpose of this study was to analyse the distribution of these cytokine gene variants in patients with rhegmatogenous retinal detachment (RD) with and without PVR. METHODS: Single nucleotide polymorphisms were analysed for five cytokines: tumour necrosis factor-alpha (TNF-alpha), transforming growth factor-beta1 (TGF-beta1), interferon-gamma (IFN-gamma), interleukin-6 (IL-6) and interleukin-10 (IL-10). Patients were divided into two surgically treated groups of RD patients: group RD had 27 patients with RD, and group PVR had 31 patients with RD complicated by PVR. A control group was composed of 46 ethnically matched healthy individuals. RESULTS: The genotype distribution of the TGF-beta1 codon 10 polymorphism differed between PVR and RD patients (p = 0.018) and between PVR patients and controls in codon 25 (p = 0.011). There was a higher frequency of TGF-beta1 codon 10 allele T in PVR patients compared with RD patients (p = 0.023). No statistically significant differences between groups were observed for the other polymorphisms examined. CONCLUSION: An association between the TGF-beta1 genetic profile and the development of PVR was detected in this study. Further studies are necessary to confirm this finding and to establish its clinical relevance.