Yavuz Bardak

Protective effects of melatonin and caffeic acid phenethyl ester against retinal oxidative stress in long-term use of mobile phone: A comparative study

There are numerous reports on the effects of electromagnetic radiation (EMR) in various cellular systems. Melatonin and caffeic acid phenethyl ester (CAPE), a component of honeybee propolis, were recently found to be potent free radical scavengers and antioxidants. Mechanisms of adverse effects of EMR indicate that reactive oxygen species may play a role in the biological effects of this radiation. The present study was carried out to compare the efficacy of the protective effects of melatonin and CAPE against retinal oxidative stress due to long-term exposure to 900 MHz EMR emitting mobile phones. Melatonin and CAPE were administered daily for 60 days to the rats prior to their EMR exposure during our study. Nitric oxide (NO, an oxidant product) levels and malondialdehyde (MDA, an index of lipid peroxidation), were used as markers of retinal oxidative stress in rats following to use of EMR. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities were studied to evaluate the changes of antioxidant status in retinal tissue. Retinal levels of NO and MDA increased in EMR exposed rats while both melatonin and CAPE caused a significant reduction in the levels of NO and MDA. Likewise, retinal SOD, GSH-Px and CAT activities decreased in EMR exposed animals while melatonin and CAPE caused a significant increase in the activities of these antioxidant enzymes. Treatment of EMR exposed rats with melatonin or CAPE increased the activities of SOD, GSH-Px and CAT to higher levels than those of control rats. In conclusion, melatonin and CAPE reduce retinal oxidative stress after long-term exposure to 900 MHz emitting mobile phone. Nevertheless, there was no statistically significant difference between the efficacies of these two antioxidants against to EMR induced oxidative stress in rat retina. The difference was in only GSH-Px activity in rat retina. Melatonin stimulated the retinal GSH-Px activity more efficiently than CAPE did.

Effect of melatonin against oxidative stress in ultraviolet-B exposed rat lens.

PURPOSE To investigate the defensive effect of melatonin against oxidative stresses in ultraviolet-B (UVB) radiation induced cataract development. METHODS Young rats received 8 kJ/m(2) UVB for 15 min. For the intervention of cataract development intraperitoneal injection of melatonin (4 mg/kg daily for 1 week) following UVB exposure was performed. Lenticular glutathione peroxidase (GSHPx), catalase (CAT), superoxide dismutase (SOD) activities and glutathione (GSH), malondialdehyde (MDA) levels were determined in UVB-melatonin, UVB, and control groups. RESULTS One week after exposure in the UVB group, lens opacities were observed and CAT, SOD, and GSHPx activities, and GSH level were lower than control and MDA level was higher than control (p < 0.05). In the UVB-melatonin group CAT and SOD activities were lower than control (p < 0.05), and the MDA level was lower than the UVB group (p < 0.05). CONCLUSIONS These results suggest that melatonin may protect against the UVB-induced cataract development by directly quenching lipid peroxides and indirectly by enhancing the production of the endogenous antioxidant GSH.

Oxidative Macromolecular Damage in Age-Related Macular Degeneration

Purpose: To evaluate oxidative damage to the macromolecules, including protein, lipid, and DNA, in association with total oxidation status (TOS), total antioxidant capacity (TAC) in patients with exudative age-related macular degeneration (AMD). Materials and Methods: Serum levels of malondialdehyde (MDA) as an index of lipid peroxidation, protein carbonyl (PC) as a marker of protein oxidation, 8-hydroxy-29-deoxyguanosine (8-OHdG) as an indicator of oxidative DNA damage along with TOS, TAC were measured by specific methods in 47 patients with exudative AMD and 25 age- and sex-matched healthy subjects. Results: Significantly higher MDA, PC, 8-OHdG, TOS, and lower TAC levels were detected in the serum of patients with exudative AMD compared with their controls (p < 0.001). Conclusion: The results indicate that an imbalance between TOS and TAC leads to not only increased lipid damage, but also protein and DNA damage. These first reported results suggest that protein and DNA damage might also play a role in the pathogenesis of AMD.

LENTICULAR CALCIUM, MAGNESIUM, AND IRON LEVELS IN DIABETIC RATS AND VERAPAMIL EFFECT

Lenticular calcium (Ca), magnesium (Mg), and iron (Fe) changes in diabetic rats and the effects of the Ca antagonist drug verapamil on this electrolyte imbalance were studied. Verapamil administration had no effect on the blood glucose values. Compared to the control group, a significant increase was observed in the lenticular Ca, Mg, and Fe content of the diabetic rats. Eight weeks of verapamil administration to the diabetic animals significantly reduced lenticular Ca, Mg, Fe values. Therefore it is suggested that verapamil might be a useful drug to prevent diabetic cataract formation.

Superoxide Dismutase, Catalase, Glutathione Peroxidase and Xanthine Oxidase in Diabetic Rat Lenses

The activities of the protective enzymes, superoxide dismutase, catalase, glutathione peroxidase and of xanthine oxidase, an enzyme acting as a source of O–2, were measured in the lenses of alloxan-induced diabetic and control rats. Superoxide dismutase and glutathione peroxidase activities were found to be significantly decreased, while catalase and xanthine oxidase activities were increased. This means that the ratio of the oxidant/antioxidant enzymes increases in the diabetic rat lens, suggesting an increased oxidative stress. This imbalance is possibly an important contributing factor in the pathogenesis of diabetic cataract.

Closed chamber iridodialysis repair using a needle with a distal hole.

We describe a closed-system technique of iridodialysis repair using a 22.0 mm, plastic handled, 27 gauge straight needle with a hole 1.0 mm proximal to the tip. The distal hole is suitable for passage of 9-0 or 10-0 mm polypropylene or nylon sutures. The technique was effective in 8 patients with traumatic iridodialysis in the upper and inferior temporal quadrants.

Nickel, chromium, manganese, iron and aluminum levels in human cataractous and normal lenses.

Atomic absorption spectrophotometry was used to detect lenticular nickel, chromium, manganese, iron and aluminum levels in 37 senile cataractous and 9 normal human lenses. The nuclear parts of the lenses were used for the study in both groups. It was found that the concentrations of nickel and iron were significantly higher, and those of chromium, manganese and aluminum were significantly lower in human cataractous lenses than those in normal human lenses. None of the elements showed a significant difference according to sex in both groups. As remarkable differences in chromium, manganese, iron, aluminum and nickel levels exist in cataractous lenses, all the five elements may play some roles in cataractogenesis.

Ocular hypotony after laser suture lysis following trabeculectomy with mitomycin C

Background: To report our experience with laser suture lysis (LSL) following trabeculectomy with mitomycin C, its timing, effectiveness and related complications. Methods: We retrospectively examined 38consecutive eyes of 36 patients that underwent LSL following trabeculectomy with mitomycin C. Results: The mean preLSL intraocular pressure (IOP) was 27.0 mm Hg (SD 6.3, range 16–39 mm Hg) and the postLSL IOP (IOP 1 h after the last session of LSL)was 16.0 mm Hg (SD 7.2, range 3–31 mm Hg). Following the LSL in 7 eyes (7 of 38) hypotony (IOP<6 mm Hg, lasting more than 24 h) developed. Two groups were defined. In group I no hypotony was found after LSL and group II went through a period of hypotony. The time interval between surgery and LSL was significantly shorter in group II (mean 5.7, SD 7.5,range 1–19 days), compared to group I (mean 14.7, SD13.0, range 1–44 days) (p=0.041). The mean final IOP(IOP measured at the last visit) was 13.3 mm Hg (SD3.4, range 6–20 mm Hg) and mean follow-up was 6.1months (SD 3.9, range 2.0–15.2 months). No hypotony was found at final examination. PostLSL IOP and final IOP were significantly lower in group II (p=0.002 and p=0.024 respectively). IOP reduction by LSL was significantly greater in group II (p=0.046). Conclusion: LSL is an effective and safe procedure to lower the IOP following trabeculectomy with mitomycin C. Early application of LSL results in lower final IOPs, but has a higher risk of hypotony.

An Unusual Complication of Retinal Reattachment Surgery

The authors report a case with an unusual late extraocular complication of scleral buckling and local silicone sponge implant. Four years after the reattachment surgery, a ptotic upper eyelid perforated by local silicone sponge implant and fistula between upper eyelid and sclera were detected. Primary repair of upper eyelid and removal of silicone sponge were performed. One year later, the retina was attached and there was no problem with the upper eyelid. Cryotherapy, episcleral explant (scleral buckling), and local implant (sponge) are frequently used and effective methods for retinal reattachment surgery. Postoperative early and late complications have been reported. To our knowledge, there is no report of upper eyelid perforation, ptosis and fistula formation caused by silicone sponge implant rejection.

Effect of verapamil on lenticular calcium, magnesium and iron in radiation exposed rats.

Purpose: To investigate the effect of verapamilon lenticular calcium, magnesium, iron and on radiation-induced cataract in rats. Methods: Thirty-seven, female, Wistar Albino rats, weighing 180–230 g were randomly grouped as follows: control group (10 rats), radiation group (13 rats) and radiation-verapamil group (14 rats). Both radiation and radiation-verapamil groups received 5 Gy radiation to the whole body in a single dose, including both eyes within the irradiation volume; in addition the verapamil group received daily subcutaneous injections of 8 mg/kg verapamil starting on the first day of radiation. At the end of an 8-week experimental period, the animals were killed by decapitation. Lenticular calcium, magnesium, and iron levels were studied. Results: The mean lens calcium level for the radiation group was significantly higher than that for the control and radiation-verapamil groups and, there was no significant difference between the control and radiation-verapamil groups. The mean lens magnesium value for the radiation group was significantly higher than that for the control group. In the radiation-verapamil group the mean lens magnesium content was significantly lower than that for the radiation group. The iron level in the radiation group was significantly higher than that for the radiation-verapamil group. Conclusions: The lens calcium, magnesium and iron contents increased after radiation exposure. Verapamil treatment significantly reduced the increase in the lenticular content of calcium, magnesium and iron, indicating a probable protective effect of verapamilin radiation-induced cataract formation.