Gülnur Andican

CALCIUM, MAGNESIUM, AND ZINC STATUS IN EXPERIMENTAL HYPERTHYROIDISM

In this study, experimental hyperthyroidism was established and used to investigate possible alterations in the calcium (Ca), magnesium (Mg), and zinc (Zn) homeostasis by assessing their concentrations in plasma and erythrocytes.In the L-thyroxine-induced hyperthyroidism condition, the experimental animals show a significant decrease in erythrocyte Ca, Mg, and Zn concentrations, and a significant decrease in plasma Mg concentration. Significant positive correlations were found for Mg and Zn both in plasma and in erythrocytes.The results suggest that the homeostasis of Ca, Mg, and Zn is altered during experimental hyperthyroidism.

Oxidized LDL and anti‐oxLDL antibody levels in peripheral atherosclerotic disease

Objective. Oxidative modification of LDL (oxLDL) is important in atherogenesis and is proposed as a useful marker for identifying patients with coronary artery disease. Antibody to oxLDL (oxLDL Ab) is detected in human sera, although its biological significance is not well established. We aimed to measure oxLDL and oxLDL Ab in peripheral atherosclerotic disease (PAD) patients, and to examine the relation between them in an attempt to understand the role of oxLDL Ab. Total risk of atherosclerosis was estimated using the global risk assessment score (GRAS) calculated on the basis of age, total cholesterol, HDL cholesterol (HDL‐Chol), diabetes, hypertension and smoking. Material and methods. Twenty‐one patients aged 63.05±9.13 years, diagnosed by peripheric angiography as PAD, and 21 healthy controls aged 47.67±13.61 years took part in the study. Total LDL and HDL cholesterol levels were determined by enzymatic methods. Levels of circulating oxLDL were measured by monoclonal antibody 4E6‐based competition ELISA. IgG class oxLDL Ab titre was measured by ELISA. Results. Compared to healthy controls, PAD patients had higher levels of oxLDL (p<0.05), oxLDL Ab (p<0.05), LDL cholesterol (LDL‐Chol) (p<0.05), total cholesterol (p<0.05) and lower HDL‐Chol (p<0.05). OxLDL was found to be positively correlated with total cholesterol (r = 0.471, p<0.05) and LDL‐Chol (r = 0.614, p<0.01) and GRAS (r = 0.435, p<0.05) and negatively with HDL‐Chol (r = −0.459, p<0.05), but not with oxLDL Ab in PAD patients. Conclusions. These findings might indicate that high LDL‐Chol levels influence the oxidation of LDL and that oxLDL is a possible marker of PAD. However, the role of oxLDL Ab in atherosclerosis remains controversial.

Oxidative damage to nuclear DNA in hyperthyroid rat liver: inability of vitamin C to prevent the damage.

The effects of hyperthyroidism on oxidative DNA damage in liver tissue and modification by vitamin C supplementation were investigated in rats. Animals were rendered hyperthyroid by administration of l-thyroxine (0.4 mg/100 g food) for 25 d. In the plasma samples, T3, T4, and thyroid-stimulating hormone (TSH) were measured by radioimmunoassay and ascorbate spectrophotometrically. Oxidative damage to hepatic nuclear DNA was determined by measuring deoxy-guanosine (dG) and 8-oxodG by high-performance liquid chromatography with diode array detector electrochemical detection (HPLC-DAD-ECD). In hyperthyroidism, 8-oxodG/ (105 dG) levels were significantly higher and plasma vitamin C levels lower than in control rats. The results of this experimental study show that oxidative damage to hepatic nuclear DNA increases in the hyperthyroid state and that vitamin C was not effective in preventing this damage.

OXIDATIVE DAMAGE TO NUCLEAR DNA IN STREPTOZOTOCIN-DIABETIC RAT LIVER

1. Accumulating evidence suggests that oxidative and glycative stress is enhanced in diabetes. Oxidative stress induces DNA damage. In the present study, we assessed the 8‐oxo‐2′‐deoxyguanosine (8‐oxodG) content of DNA, an indicator of oxidative DNA damage, in streptozotocin (STZ)‐induced diabetic (n = 21) and control rats (n = 18).

Biochemical Evaluation of Oxidative Stress during Exercise in Patients with Coronary Heart Disease

Abstract The impact of exercise tolerance test on oxidative stress was assessed by thiobarbituric acid reactive substances and markers of antioxidant status, namely Cu Zn superoxide dismutase, glutathione peroxidase, glutathione and vitamin E in blood samples of patients with exertional angina. The study was aimed to differentiate patients with positive exercise test (coronary heart disease patients) from patients with negative exercise test, at rest and peak exercise with respect to the investigated variables. Significantly lower values for both glutathione peroxidase activity and glutathione level were observed in patients after exercise test (p﹤0.01 and p﹤0.05, respectively). Only the patients with positive exercise test had significantly lower values for Cu Zn superoxide dismutase, glutathione peroxidase and glutathione, and a significantly higher ratio of thiobarbituric acid reactive substances/glutathione after exercise, as compared to before (p﹤0.05, p﹤0.05, p﹤0.05, p﹤0.01, respectively). Our findings indicate that the exercise test applied to patients with exertional angina oxidatively stresses the erythrocytes to a greater extent in exercise test (+) patients than in exercise test (−) patients.

Inflammatory hypothesis as a link between Alzheimer's disease and diabetes mellitus

The aim of the present study was to evaluate whether there was an inflammation‐mediated link between Alzheimers disease (AD) and type 2 diabetes mellitus (DM) status.