Browsing by Author "Topal, Ahmet"

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A Couple of Novel Image Enhancement Methods Depending on the Prabhakar Fractional Approaches
(Springer London Ltd, 2024) Topal, Ahmet; Aydin, Mustafa
Integrating fractional calculus into image processing techniques offers a useful and robust approach. In this study, we proposed contrast enhancement filters using Prabhakar fractional integral operator based on Grunwald-Letnikov and forward Euler. We evaluated the performance of the proposed enhancement methods on both high and low contrast images and compared them with fractional and non-fractional contrast enhancement methods. To demonstrate the superiority of our methods, we employed five different image quality metrics: PSNR, MSE, SSIM, FSIM, and entropy. For low contrast images, our methods not only achieved acceptable results for each metric-PSNR values above 25, SSIM values above 0.9, MSE values below 200, FSIM values above 0.97, and entropy values above 7-but also demonstrated better performance compared to other methods. In high contrast images, despite an overall decline in metric scores, the Grunwald-Letnikov based method remains the leading approach among both fractional and non-fractional methods. Additionally, empirical results provide evidence that the proposed methods are more effective in enhancing low contrast images compared to high contrast images.
Investigation of 8-Ohdg, Cyp1a, Hsp70 and Transcriptional Analyses of Antioxidant Defence System in Liver Tissues of Rainbow Trout Exposed To Eprinomectin
(Academic Press Ltd- Elsevier Science Ltd, 2017) Alak, Gonca; Yeltekin, Ash Cilingir; Tas, Ismail Hakki; Ucar, Arzu; Parlak, Veysel; Topal, Ahmet; Atamanalp, Muhammed
Eprinomectin (EPM), a member of avermectin family, is a semi-synthetic antibiotic. It has been known that avermectin family enters the aquatic environments and adversely affects the aquatic organisms. Effects of EPM is fully unknown in aquatic organisms especially fish, thus the aim of the present study was to investigate transcriptional changes (sod, cat, gpx) and activities of some antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) and malondialdehyde (MDA) levels, oxidative DNA damage (8-hydroxy-2-deoxyguanosine (8-OHdG)) and transcriptional changes of heat shock protein 70 (HSP70), and cytochromes P4501A (CYP1A) in liver tissues of rainbow trout exposed to sublethal EPM concentration (0.001 mu g/L, 0.002 mu g/L, 0.01 mu gL, 0.05 mu g/L) for 24 h, 48 h, 72 h and 96 h. The decrease in antioxidant enzyme (SOD, CAT and GPx) activity, transcriptional changes (sod, cat, gpx, HSP70 and CYP1A genes) and increase in MDA level and activity of 8-OHdG in a dose-time-dependent manner in the liver of rainbow trout were observed. The down-regulated of antioxidant (sod, cat and gpx), HSP70 and CYP1A obviously, the severity of which increased with the concentration of EPM and exposure time. The results imply that EPM could induce oxidative damage to the liver tissue of rainbow trout. The information presented in this study is helpful to understand the mechanism of veterinary pharmaceuticals-induced oxidative stress in fishes. (C) 2017 Elsevier Ltd. All rights reserved.
Investigation of 8-Ohdg, Cyp1a, Hsp70 and Transcriptional Analyses of Antioxidant Defence System in Liver Tissues of Rainbow Trout Exposed To Eprinomectin (Vol 65, Pg 136, 2017)
(Academic Press Ltd- Elsevier Science Ltd, 2018) Alak, Gonca; Yeltekin, Asli Cilingir; Tas, Ismail Hakki; Ucar, Arzu; Parlak, Veysel; Topal, Ahmet; Atamanalp, Muhammed
Neurotoxic Responses in Brain Tissues of Rainbow Trout Exposed To Imidacloprid Pesticide: Assessment of 8-Hydroxy Activity, Oxidative Stress and Acetylcholinesterase Activity
(Pergamon-elsevier Science Ltd, 2017) Topal, Ahmet; Alak, Gonca; Ozkaraca, Mustafa; Yeltekin, Ash Cilingir; Comakli, Selim; Acil, Gurdal; Atamanalp, Muhammed
The extensive use of imidacloprid, a neonicotinoid insecticide, causes undesirable toxicity in non targeted organisms including fish in aquatic environments. We investigated neurotoxic responses by observing 8-hydroxy-2-deoxyguanosine (8-OHdG) activity, oxidative stress and acetylcholinesterase (AChE) activity in rainbow trout brain tissue after 21 days of imidacloprid exposure at levels of (5 mg/L, 10 mg/L, 20 mg/L). The obtained results indicated that 8-OHdG activity did not change in fish exposed to 5 mg/L of imidacloprid, but 10 mg/L and 20 mg/L of imidacloprid significantly increased 8-OHdG activity compared to the control (p < 0.05). An immunopositiv reaction to 8-OHdG was detected in brain tissues. The brain tissues indicated a significant increase in antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)) compared to the control and there was a significant increase in malondialdehyde (MDA) levels (p < 0.05). High concentrations of imidacloprid caused a significant decrease in AChE enzyme activity (p < 0.05). These results suggested that imidacloprid can be neurotoxic to fish by promoting AChE inhibition, an increase in 8-OHdG activity and changes in oxidative stress parameters. Therefore, these data may reflect one of the molecular pathways that play a role in imidacloprid toxicity. (C) 2017 Elsevier Ltd. All rights reserved.
The Protective Effect Exerted by Dietary Borax on Toxicity Metabolism in Rainbow Trout (Oncorhynchus Mykiss) Tissues
(Elsevier Science inc, 2019) Alak, Gonca; Parlak, Veysel; Yeltekin, Asli Cilingir; Ucar, Arzu; Comakli, Selim; Topal, Ahmet; Turkez, Hasan
The aim of this study was to evaluate the effectiveness of borax (BX) against heavy metal exposure on the transcriptional and biochemical reaction in vivo and alleviating effect on gill and liver tissues of rainbow trout. Due to this aim, fish were fed with different level of BX and/or copper (Cu) (1.25, 2.5 and 5 mg/kg of BX; 500 and 1000 mg/kg of Cu) for 21.days in pre- and co-treatment options. The transcriptional parameters [(heat-shock protein 70 (hsp70), and cytochromes P450 (cyp1a), glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT))], antioxidant enzyme activities (SOD, CAT and GPx), malondialdehyde (MDA), oxidative DNA damage (8-hydroxy-2'-deoxyguanosine (8-OHdG) and caspase-3 levels were investigated in different tissues samples of treated and control fish. Our results revealed that antioxidant enzyme activity was increased and levels of 8-OHdG, Caspase-3 and MDA were decreased in the BX and BX combined groups as compared to the copper combination group and to copper-only application during pre- and co-treatment (p < 0.05). Similarly, hsp70 and cyp1a gene expressions were decreased after treatment with BX. As conclusion, we suggest that borax itself is not an antioxidant it supportes antioxidant defense mechanism of fish disrupted by heavy metals.