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Ibrahim M.A.,National Research Center of Egypt | Gawad A.E.-D.A.,Egyptian Research Institute of Ophthalmology
Journal of Computational and Theoretical Nanoscience

As a result of emerging applications of chitosan this paper is dedicated to study the possible interaction of amino acids with chitosan. Semiemperical molecular modeling technique is applied to assess the interaction of amino acids (alanine, asparagines, aspartic, arginine, cysteine, glutamine, glycine and tryptophan) with chitosan. Results indicate the selectivity of chitosan furthermore we introduce the site whereas amino acid could interact with chitosan. Chitosan is interacting with amino acid through NH2 group. It is concluded that chitosan is acting with amino acids like protein interaction which dedicate chitosan for many applications in the biological system. Copyright © 2012 American Scientific Publishers. Source

PURPOSE:: To assess the clinical outcomes after sequential surgical implantation of intracorneal ring segments and transepithelial corneal collagen cross-linking (TE-CXL) in keratoconic eyes. METHODS:: In this consecutive randomized study, 40 eyes of 29 patients with progressive mild to moderate keratoconus were included and were randomly divided into two groups. Group 1 included 20 eyes that underwent Keraring implantation, and group 2 included 20 eyes that underwent Keraring insertion followed by TE-CXL 1 month later. In both groups, channel creation was performed manually. Visual, refractive, and topographic outcomes were measured preoperatively and 1, 3, and 6 months postoperatively. RESULTS:: There was statistically significant improvement in both groups regarding uncorrected distance visual acuity (P < 0.001) and corrected distance visual acuity (P < 0.001), with a significant reduction in the refractive error and keratometric values (P < 0.001). There was no statistically significant difference between both groups regarding changes in uncorrected distance visual acuity, corrected distance visual acuity, and refractive error (P > 0.05). However, group 2 revealed a more statistically significant reduction in spherical refraction after 3 months (P = 0.04) and highly significant improvement after 6 months (P = 0.004). CONCLUSIONS:: Intracorneal ring segment implantation is an effective procedure for visual and refractive improvement in keratoconic eyes. The addition of TE-CXL to the procedure compensates for residual superficial irregularities, disrupts the progression of the disease, and provides greater improvements in spherical values. The process is simply a deep stretch with superficial lamellar stiffness. © 2015 Wolters Kluwer Health, Inc. All rights reserved. Source

Abdelkawi S.A.,Egyptian Research Institute of Ophthalmology
General physiology and biophysics

The aim of the present study was to evaluate the change in corneal protein and oxidative stress state after using photodynamic therapy (PDT) for treatment of experimental corneal neovascularization (NV) with benzoporphyrin derivative (BPD). One group was considered as control (N = 10 eyes), corneal NV was induced in 25 New Zealand male rabbits (N = 50 eyes) after placing silk sutures in the corneal limbus. Five rabbits with corneal NV were left without any treatment, and 20 rabbits were administered by intravenous injection with Verteporfin at a dose of 1.5 mg/kg. Diode laser (660 nm) was applied for 5 minutes with a power of 50 mW/cm2. For a period of 4 weeks, five rabbits were selected and sacrificed weekly (N = 10 eyes each). The corneas were isolated for determination of protein content, SDS-PAGE, total antioxidant capacity (TAC), total oxidative capacity (TOC), malondialdhyde (MDA) and oxidative stress index (OSI). The results indicated that corneal NV induced changes in the content and composition on the corneal protein and gradual improvement of the cornea after the 3rd and 4th week of PDT was detected. Furthermore, the oxidative/antioxidative balance shifted towards the antioxidative status that helped to prevent further damage. Source

Abdelkawi S.,Egyptian Research Institute of Ophthalmology
International Journal of Radiation Biology

Purpose: This study was aimed at determining the effect of whole body irradiation with single and fractionated low doses of γ-radiation on the structure of normal rats lens crystallin with the concept of correlating this with the changes in its molecular weight. Materials and methods: Three groups of Wistar albino rats were involved in this study; the first group is the control (n 10) and the second group (n 10) treated with a single dose of 4.0 Gy administered in one application from Cesium-137. The third group (n 60) was treated for 8 weeks with fractionated dose rate of 0.5 Gy/week. Lens crystallin was analysed for protein content measurements and column chromatography. Results: Measurements of total soluble lens protein indicated pronounced decreases after exposure to single and fractionated doses of γ-radiation. The molecular weights and the protein content for the βH (with high molecular weight), βL (with low molecular weight) and γ-crystallin fractions revealed generalized alteration for all groups. Conclusion: Single and fractionated doses of γ-radiations induced lens crystallin changes that might lead to development of cataract due to induction of cross-linking and aggregation. βH-crystallin was the most stable against radiation induced damage, and the molecular weight of γ-crystallin was the most sensitive to gamma radiation. © 2012 Informa UK, Ltd. Source

Taher E.,Egyptian Research Institute of Ophthalmology
Türkiye parazitolojii dergisi / Türkiye Parazitoloji Derneǧi = Acta parasitologica Turcica / Turkish Society for Parasitology

Four plant extracts possessing molluscicidal and insecticidal efficacy were evaluated under laboratory conditions versus Biomphalaria alexandrina, Lymnea cailliaudi snails, their egg masses and Culex pipiens larvae. These extracts included Grape seed, Eucalyptus, Pomegranate, Verbesina alcoholic extracts, as well as Eucalyptus oil. Different mortalities in the exposed vectors were recorded due to the four plant extracts using different concentrations and exposure time. Total snail mortality LC < sub > 100 < /sub > was (100 ppm/12-24h) for Grape seed, (200 ppm/18-24h) for Eucalyptus, (100 ppm/12-18h) for Pomegranate, (100-200 ppm/24h) for Verbesina alcoholic extracts and (100-200 ppm/12h) for Eucalyptus oil. However, only Eucalyptus, Verbesina alcoholic extracts and Eucalyptus oil revealed snail ovicidal effects. LC < sub > 100 < /sub > was (100-200 ppm/24h), (100-200 ppm/24h) & (100-200 ppm/12-48h) respectively. Moreover, the same plant extracts were able to induce total Culex pipiens larvicidal mortality, LC < sub > 100 < /sub > was (200 ppm/48h). However, Grape seed and Pomegranate alcoholic extracts did not induce either snail ovicidal or Culex pipiens larvicidal total mortalities. Activities of the studied plant extracts were considered using reference molluscicidal (Copper sulfate) and insecticidal (Temephos) substances. Egyptian native plants continue to provide a wealth of potential sources for biologically active agents that may have a promising role in the production of safe, biodegradable eco-friendly and natural molluscicidal and insecticidal agents. Source

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