Ferda Akar

Comparison of In Vitro Antimicrobial Susceptibility in Flavobacterium psychrophilum Isolated from Rainbow Trout Fry

The aim of this study was to demonstrate the presence of Flavobacterium psychrophilum in the west Aegean region of Turkey and to evaluate the in vitro susceptibility of F. psychrophilum (isolated from the fry of rainbow trout Oncorhynchus mykiss) to seven antimicrobial agents, as determined by the disk diffusion and agar dilution methods. A total of 250 rainbow trout fry (weight = 2-5 g; total length = 3-6 cm) were examined, and 20 bacterial isolates were phenotypically identified. Antimicrobial agents included in this investigation were amoxicillin-clavulanic acid (AMC), erythromycin (E), enrofloxacin (ENR), florfenicol (FFC), gentamicin (CN), oxytetracycline (OT), and sulfamethoxazole-trimethoprim (SXT). Disk diffusion and agar dilution methods were performed according to published standards. Minimum inhibitory concentration (MIC) ranges were determined using the agar dilution method for F. psychrophilum isolates. Resistance of F. psychrophilum to CN (disk diffusion method: 70%; agar dilution method: 95%), E (65%; 100%), and SXT (75%; 100%) was high using both methods. Resistance to ENR (10%; 15%) and FFC (25%; 25%) was low with both methods; MIC90 (minimum concentration required to inhibit bacterial growth by 90%) was 4 microg/mL for ENR and 16 microg/mL for FFC. Ninety percent of the F. psychrophilum isolates were resistant to AMC based on the disk diffusion method, while only 15% of isolates showed resistance based on the agar dilution method. For OT, 20% of isolates were resistant based on disk diffusion, while 75% exhibited resistance based on agar dilution. The importance of susceptibility testing when facing an outbreak of F. psychrophilum at a fish farm is obvious; however, the discrepancies between testing methods for AMC and OT require further studies.

Effects of xylene and formaldehyde inhalations on renal oxidative stress and some serum biochemical parameters in rats.

In this study, it was aimed to demonstrate the possible renal oxidative stress and some serum biochemical parameters and their alterations caused by the exposure to xylene and formaldehyde (HCHO) in rats. Weighing 150—200 g, 12-week-old, 24 female Sprague-Dawley rats were used. The rats were randomly divided into four groups: Group 1 (control), Group 2 (300-ppm technical xylene), Group 3 (6-ppm HCHO) and Group 4 (150-ppm technical xylene + 3-ppm HCHO). The animals were exposed to gases eight hours per day for six weeks. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities, glutathione (GSH) and malondialdehyde (MDA) levels were measured. In addition, serum total protein, albumin, urea and creatinine levels were evaluated. Compared with the control animals, urea levels increased significantly in all groups (P < 0.001). GSH activities and MDA levels increased in xylene and xylene + HCHO groups (P < 0.05). No statistically considerable differences were found in SOD, CAT and GSH-Px activities, total protein, albumin and creatinine levels among all groups (P > 0.05). The present study indicates but not statistically confirms the renal toxicity of the exposures to xylene, HCHO and a mixture of them.

The protective effects of vitamin C on the DNA damage, antioxidant defenses and aorta histopathology in chronic hyperhomocysteinemia induced rats

The aim of this study was to investigate the protective effect of vitamin C towards hyperhomocysteinemia (hHcy) induced oxidative DNA damage using the comet assay. The increase in plasma homocysteine levels is an important risk factor for vascular and cardiovascular diseases through free radical production. This study was also conducted to investigate the histopathological changes in the thoracic aorta and the oxidant/antioxidant status in heart, liver and kidney tissues. Twenty-four adult male Wistar rats were divided as control, hHcy and hHcy+vitamin C group. Chronic hHcy was induced by oral administration of l-methionine (1g/kg/day) for 28 days. Vitamin C was given 150mg/kg/day within the specified days. DNA damage was measured by use of the comet assay in lymphocytes. Levels of malondialdehyde (MDA) and glutathione (GSH) as well as catalase (CAT) and superoxide dismutase (SOD) activities were determined in heart, liver and renal tissues. Results show that l-methionine administration significantly increased % Tail DNA and Mean Tail Moment in hHcy group as compared with other groups. Vitamin C treatment significantly decreased the high MDA levels and increased activity of antioxidant enzymes in tissues. Aortic diameter and thickness of aortic elastic laminae were significantly lower in hHcy+vitamin C group. Comet assay can be used for the assessment of primary DNA damage caused by hHcy. Histopathological findings showed that vitamin C may have a preventive effect in alleviating the negative effects of hHcy. Vitamin C might be useful in the prevention of endothelial dysfunction caused by hHcy.