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    Effect of melatonin treatment on liver and thymus zinc levels in young and middle-aged rats
    (WILEY-LISS, 2004) Ozturk, G; Akbulut, KG; Afrasyap, L; Sevinc, D
    Melatonin (MEL) is the main neurohormone of the pineal gland. Zinc (Zn) is an essential trace element that is required as a catalytic component for more than 200 enzymes. Both MEL and Zn are considered beneficial for anti-immunosenescence. Recent Findings have shown that MEL can modulate Zn turnover. The aim of this study was to investigate the effect of MEL treatment on the tissue Zn levels in young (4 months) and middle-aged (14 months) rats. Male wistar rats received during 3 weeks subcutaneous injection of MEL (10 mg/kg). After 3 weeks, rats were decapitated and tissue samples were collected. Zn levels were measured by spectrophotometric assay. In conclusion, MEL decreased liver Zn levels both in young and middle-aged rats. In addition, Zn levels in young control group were significantly higher than middle-aged control group. However, MEL treatment increased thymus Zn levels in middle-aged group compared with the control. These findings indicate that tissue Zn levels are significantly affected by MEL treatment.
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    L-arginine and mitomycin C-induced nitric oxide release and apoptosis in human lymphocytes
    (ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD, 2003) Erden, CD; Ekmekci, A; Sahin, FI; Ergun, MA; Ozturk, G; Erbas, D
    Nitric oxide (NO) is a free radical that is produced by a number of mammalian cell types from L-arginine and a critical mediator that acts in many tissues to regulate a diverse range of physiological processes. The major metabolic end product for NO is nitrate (NO2) and nitrite (NO2), which are stable metabolites within tissue, plasma, and urine. Measurements of nitrate and nitrite values reveal alterations in NO production. Endogenously generated or exogenously applied NO causes DNA cleavage by endonuclease activation. We investigated the effect Of L-arginine and mitomycin C (MMC) on cultured lymphocytes of healthy individuals. We observed chromosome breaks, apoptotic cells and increased NO levels after L-arginine and MMC addition. In conclusion, our results confirmed that NO may be the cause of apoptotic cell death in L-arginine added lymphocyte culture. (C) 2003 Elsevier Science Ltd. All rights reserved.
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    NO level and endothelial NO synthase gene polymorphism (Glu298Asp) in the patients with coronary artery disease from the Turkish population
    (OXFORD UNIV PRESS, 2004) Afrasyap, L; Ozturk, G
    Nitric oxide is synthesized from L-arginine by endothelial nitric oxide synthase encoded by eNOS gene. This study was performed to investigate the relationship between the serum nitric oxide level and eNOS gene polymorphism in the Turkish population with angiographically diagnosed coronary artery disease (63.47 +/- 9.10 years old, n=250) and control subjects without any history and/or risk factors of coronary artery disease (60.71 +/- 9.14 years old, n=150). Griess assay and PCR-RFLP analysis were used to measure the serum nitric oxide metabolites and genotypes, respectively. It was found that Glu/Glu, Glu/Asp and Asp/Asp genotype frequencies of the eNOS were 49.3%, 41.3% and 9.3% respectively in the control group, and 45.6%, 41.2% and 13.2% in the patient group. Serum nitric oxide levels were (32.56 +/- 17.26) muM in controls and (29.84 +/- 11.88) muM in patients. Neither the frequencies of the Glu298Asp genotypes nor the serum nitric oxide levels showed a significant difference between the groups. There was also no correlation between serum nitric oxide levels and the frequencies of the eNOS genotypes. Result showed that the coronary artery disease of the Turkish population seemed to develop without any alterations in eNOS Glu298Asp genotype frequency and the serum nitric oxide level.
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    Prognostic role of serum vascular endothelial growth factor, basic fibroblast growth factor and nitric oxide in patients with colorectal carcinoma
    (ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD, 2002) Akbulut, H; Altuntas, F; Akbulut, KG; Ozturk, G; Cindoruk, M; Unal, E; Icli, F
    Recently, angiogenesis has gained an increasing interest as a prognostic factor in a variety of solid tumours. In this study we aimed to assess the prognostic role of serum vascular endothelial growth factor (VEGF), basic fibroblast growth factor (b-FGF) and nitric oxide (NO) levels in patients with colorectal carcinoma (CRC). A total of 52 consecutive colorectal cancer patients with stage I to IV disease was included. In addition to routine laboratory and staging procedures, serum VEGF, b-FGF levels, and nitrate levels as a surrogate marker for in-vivo NO production were assayed. Serum VEGF concentrations, adjusted to the platelet count were found to be a significant factor for overall survival in univariate analysis (P = 0.033). A new angiogenic index (AI), derived from serum VEGF and nitrate concentrations, was established. AI is the only independent prognostic factor of survival in all patients (P = 0.008, Cox regression analysis). Likewise, AI is also significant prognostic factor for disease-free survival (DFS) in patients with operable CRC (P = 0.032, Cox regression analysis). In conclusion, serum VEGF and NO levels have prognostic role in patients with CRC and the new angiogenesis index using the serum levels of the factors seem to be useful. (C) 2002 Elsevier Science Ltd. All rights reserved.
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    Ratios of homocysteine and nitrite to high-density lipoprotein in coronary artery patients with the different degree of stenosis
    (ELSEVIER SCIENCE INC, 2004) Afrasyap, L; Ozturk, G
    Although the interaction between Hcy, NO2- and vascular disease has been extensively studied, there are no data verifying their ratios to HDL-C in coronary artery disease (CAD). We examined whether Hcy/HDL-C and NO2-/HDL-C ratios correlated with the degree of stenosis in CAD. Also, TC/HDL-C and LDL-C/HDL-C ratios were evaluated in the same individuals. Seventy subjects were divided into three groups according to coronary angiography findings: >50% stenosis (n=35, years: 50.9+/-3.4; Group 1), 5-50% stenosis (n=20, years: 50.6+/-3.8; Group 2), <5% narrowing (n=15, years: 49.0+/-3.2; control group). Hcy/HDL-C, NO2-/HDL-C, TC/HDL-C and LDL-C/HDL-C were statistically higher in both Group 1 patients (p=0.001, for all ratios) and Group 2 patients (p=0.001, p=0.001, p=0.03, 0.041, respectively) with respect to controls. The values were correlated with the degree of stenosis in the different significance levels (r=0.496, p=0.001; r=0.384, p=0.004; r=0.334, p=0.012; r=0.321, p=0.016, respectively). In patients with >50% stenosis, NO2-/HDL-C was only shown to change significantly in relation to obstructive artery number (p=0.026) and also showed a positive correlation (r=0.379, p=0.032). In conclusion, Hcy/HDL-C and NO2-/HDL-C appear to be more indicative than TC/HDL-C and LDL-C/HDL-C in the evaluation of CAD patients regarding the degree of stenosis. However, only NO2-/HDL evaluation seems to be a reliable indicator in the patients with heavy stenosis of CAD. Further studies are needed to confirm the results of present study. (C) 2004 Elsevier Inc. All rights reserved.