Levent Altintas

Effects of subconjunctivally injected bevacizumab, etanercept, and the combination of both drugs on experimental corneal neovascularization.

OBJECTIVE To compare the effect of subconjunctivally injected bevacizumab, etanercept and the combination of both drugs on experimental corneal neovascularization in rats. DESIGN Experimental study. PARTICIPANTS 28 male Wistar-Albino rats. METHODS Right corneas of rats were cauterized by silver nitrate sticks. Rats were divided randomly and equally into 4 groups so that each group contained 7 subjects. Immediately after the cauterization, 0.05 ml normal saline was injected subconjunctivally in group 1 (control group); 0.05 ml (1.25 mg) bevacizumab was injected subconjunctivally in group 2; 0.05 ml (1.25 mg) etanercept was injected subconjunctivally in group 3; 0.05 ml (1.25 mg) bevacizumab and 0.05 ml (1.25 mg) etanercept was injected subconjunctivally in group 4. The rats were euthanized on the 8th day, and digital photographs were obtained before the eyes were enucleated. The area of corneal neovascularization was calculated from digital photographs. Corneal sections were analyzed by histopathologically. RESULTS The burn stimulus score was +1 or higher in all eyes. The difference of the neovascularization score between groups was found to be statistically significant (p = 0.001). The area of corneal neovascularization was 79.8% in group 1, 43.2% in group 2, 54.5% in group 3, and 34.8% in group 4. In group 4, corneal neovascularization was inhibited more than in the other groups. Histologic examination showed that the treatment groups had less neovascularization, inflammation, and fibroblast activity than the control group (p< 0.05). CONCLUSIONS Our study has shown that etanercept does have some antiangiogenic and anti-inflammatory effects in treatment of corneal neovascularization. The combination of bevacizumab and etanercept may be a promising approach in the treatment of corneal neovascularization.

A New Teamwork-Based PBL Problem Design for Electrical and Electronic Engineering Education: A Systems Approach

Engineers today are required both to have traditional technological skills and to be competent with a variety of soft skills such as team-working and the ability to present or sell their ideas. Changes in professional requirements impose demands on the teaching methods in universities. In this day of mass information, the ability to find and filter out the right information is a necessity in all walks of life. Success in professional life requires one to be able to work independently and as part of a team, always being ready to take the initiative, and to acquire new knowledge. Acquiring these professional skills requires good social skills and learning abilities, which employers emphasise. A good engineer is able to identify and define a problem and find a working solution. Our paper shows that the problem-based learning (PBL) approach is an effective method to cope with these changes and demands.

Comparison of the effects of subconjunctival and topical anti-VEGF therapy (bevacizumab) on experimental corneal neovascularization.

PURPOSE To compare the effects of bevacizumab applied either subconjunctivally or topically, in a rat model of corneal neovascularization induced by alkali burn. METHODS The right corneas of 24 Wistar-Albino rats were cauterized with silver nitrate sticks. The rats were divided randomly and equally into three groups: no treatment control (n=8), subconjunctival bevacizumab treatment (n=8), and topical bevacizumab treatment (n=8). Immediately following cauterization, the subconjunctival group was treated with a 0.05 ml (1.25 mg) bevacizumab subconjunctival injection. The topical group was treated with 10 mg/ml bevacizumab twice daily, and the control group received subconjunctival saline injections twice daily. The burn stimulus and neovascularization scores were evaluated using a technique previously described by Mahoney and Waterbury. Digital photographs were obtained before the eyes were enucleated and corneal sections were then analyzed by histopathology. RESULTS The mean burn stimulus score was 1.86 ± 0.6 and there was no statistical difference between the groups (p=0.730). The mean neovascularization scores in the subconjunctival and topical bevacizumab groups were statistically lower than the control group (p<0.05). The mean percentage area of corneal neovascularization was 82.5 ± 22.1 in the control group, 42.7 ± 15.0 in the subconjunctival group, and 55.8 ± 18.2 in the topical group. The differences between the control and treatment groups were statistically significant (p<0.05). Histopathology showed that the treatment groups presented less neovascularization, inflammation, and fibroblast activity than the control group (p<0.05). CONCLUSIONS This study demonstrates that both subconjunctival and topical administrations of bevacizumab inhibit corneal neovascularization and decrease inflammation and fibroblast activity in a rat model of corneal neovascularization induced by alkali burn.

An observation tool for instructor and student behaviors to measure in-class learner engagement: a validation study

Background Efforts are made to enhance in-class learner engagement because it stimulates and enhances learning. However, it is not easy to quantify learner engagement. This study aimed to develop and validate an observation tool for instructor and student behaviors to determine and compare in-class learner engagement levels in four different class types delivered by the same instructor. Methods Observer pairs observed instructor and student behaviors during lectures in large class (LLC, n=2) with third-year medical students, lectures in small class (LSC, n=6) and case-based teaching sessions (CBT, n=4) with fifth-year students, and problem-based learning (PBL) sessions (~7 hours) with second-year students. The observation tool was a revised form of STROBE, an instrument for recording behaviors of an instructor and four randomly selected students as snapshots for 5-min cycles. Instructor and student behaviors were scored 1–5 on this tool named ‘in-class engagement measure (IEM)’. The IEM scores were parallel to the degree of behaviors contribution to active student engagement, so higher scores were associated with more in-class learner engagement. Additionally, the number of questions asked by the instructor and students were recorded. A total of 203 5-min observations were performed (LLC 20, LSC 85, CBT 50, and PBL 48). Results Interobserver agreement on instructor and student behaviors was 93.7% (κ=0.87) and 80.6% (κ=0.71), respectively. Higher median IEM scores were found in student-centered and problem-oriented methods such as CBT and PBL. A moderate correlation was found between instructor and student behaviors (r=0.689). Conclusions This study provides some evidence for validity of the IEM scores as a measure of student engagement in different class types.

Anterior Visual Pathways in Amblyopia: Quantitative Assessment With Diffusion Tensor Imaging

PURPOSE To detect the abnormalities of the anterior visual pathways in children with amblyopia with diffusion tensor imaging. METHODS Ten children with unilateral amblyopia, 5 children with bilateral amblyopia, and 10 control children were treated using diffusion tensor imaging scanning in this institutional practice. Fractional anisotropy and mean diffusivity values were analyzed using diffusion tensor imaging in the prechiasmatic and chiasmatic regions. Fractional anisotropy and mean diffusivity values of the amblyopic groups were compared with the values of the control group using the Kruskal–Wallis test. The Mann–Whitney U test was used to evaluate pairwise differences between groups. RESULTS When compared with the control group, prechiasmatic fractional anisotropy values were significantly decreased in both affected and sound fellow eyes in the unilateral amblyopic group (P = .019 and .013), but not in the bilateral amblyopic group (P = .221). Mean diffusivity values were significantly greater in the sound fellow eye in the unilateral amblyopic group in the prechiasmatic region (P = .001 and .049). CONCLUSION Diffusion tensor imaging showed a significant decrease in fractional anisotropy and an increase in mean diffusivity values in the unilateral amblyopic group in both affected and sound fellow eyes. These findings may reflect axonal underdevelopment in anterior pathways, particularly in the unilateral amblyopic group.

Optical Coherence Tomography Measurement of Retinal Nerve Fibre Layer, Optic Nerve Head and Macula in Normal Subjects

The aim of the study was to evaluate the variation in retinal nerve fibre layer (RNFL), optic nerve head (ONH) and macular measurements in healthy Turkish subjects using Stratus optical coherence tomography (OCT). The design is a cross-sectional study of 398 eyes in 199 normal subjects aged between 5 and 70 years. The participants underwent a detailed ophthalmologic examination including imaging with Stratus OCT. RNFL, optic disc and macula fast scan methods were used to obtain the peripapillary RNFL thickness, ONH and macular parameters. The effects on the findings of age, gender and laterality of the eye tested were assessed. The average RNFL thickness and the thickness measured in the superior and temporal quadrants were statistically significantly negatively correlated with age. Similar results were found for mean macular thickness, macular RNFL thickness and for total macular volume. There was no effect of age on ONH measurements. The RNFL thickness in the temporal quadrant was significantly greater in females than in males (p<0.05). The mean macular thickness in 1–3 mm was greater in males than in females (p<0.05). The nasal RNFL thickness was significantly thicker in the right eyes than in the left eyes (p<0.05). We conclude that, in healthy subjects, as age increases there is a significant reduction in peripapillary and macular RNFL thickness and in macular thickness and volume. The hypothesis that RNFL and macular measurements are not symmetrical between the two eyes merits further study.