Meral Torun

PLASMA MALONDIALDEHYDE (MDA) LEVELS IN BREAST AND LUNG CANCER PATIENTS

Objective: To measure the levels of malondialdehyde (MDA), a marker of lipid peroxidation, in patients with breast and lung cancer.

Lipid peroxidation and antioxidant status in blood and tissue of malignant breast tumor and benign breast disease

Changes in the levels of malondialdehyde (MDA), nitrate and nitrite (as an index of nitric oxide production), lipid hydroperoxide (LOH), total antioxidant capacity (TAC), lipids (total cholesterol and triglycerides) and lipoproteins (HDL‐ and LDL‐cholesterol) were estimated in breast cancer patients (n = 15) and benign breast disease (n = 15). Serum and tissue MDA levels were found to be decreased in breast cancer patients compared to the benign group (p < 0.05). In contrast, nitrate and nitrite levels were increased in serum and tissue of the cancer group compared to benign breast disease patients (p < 0.05). Compared to the benign group, tissue TAC levels were elevated in the breast cancer patient group (p < 0.05). Total cholesterol and HDL‐cholesterol were elevated in the benign group compared with cancer patients (p < 0.05). These findings support the hypothesis that lipid peroxidation in serum and tissue of benign breast disease is greater than in breast cancer. However, the enhanced levels of nitric oxide may be in response to inflammation in patients with breast cancer. Total antioxidant status is lower in benign tissue than in cancerous tissue, probably to compensate for this elevated free radical production.

Oxidation of Uric Acid in Rheumatoid Arthritis: Is Allantoin a Marker of Oxidative Stress?

Free radicals are implicated in many diseases including atherosclerosis, cancer and also in rheumatoid arthritis. Reaction of uric acid with free radicals, such as hydroxyl radical and hypochlorous acid (HOCl) results in allantoin production. In this study, we measured the serum allantoin levels, oxidation products of uric acid, as a marker of free radical generation in rheumatoid arthritis. Fasting blood samples were obtained from 21 rheumatoid patients and 15 healthy controls. In this study, the serum allantoin and uric acid levels were measured by a gas chromatography–mass spectrometry method and the ratios were calculated. The mean allantoin and uric acid levels and ratios in the patient group were 22.1±11.3, 280.5±65.0 and 8.0±3.7 μM, while in the control group they were 13.6±6.3, 278.3±53.6 and 4.9±2.1 μM, respectively. The effects of gender, age, menopausal status, duration of disease and medications on serum allantoin and uric acid levels of the patient and control groups were studied. Our results suggest that uric acid acts as a free radical scavenger and thus is converted to allantoin. Increased allantoin levels suggest the possible involvement of free radicals in rheumatoid arthritis.

Serum β–carotene, vitamin E, vitamin C and malondialdehyde levels in several types of cancer

We measured the levels of serum carotenoids (β–carotene), total tocopherol (vitamin E), ascorbic acid and malondialdehyde (MDA) in newly diagnosed cancer cases. Levels of the antioxidants and MDA in serum samples from 208 subjects with cancer affecting different sites (59 breast, 38 head and neck, 46 genitourinary, 12 lung, 20 gastrointestinal and 33 other sites) were compared with levels in 156 controls. Cases and controls were compared with respect to a number of potentially confounding factors: age, sex, smoking status, Quetelet index (kg/m2), diet and alcohol intake. Mean (±SD) levels of β–carotene, vitamin E and vitamin C were significantly lower among the cases than the controls (49 35±36 55 μg/1, 0 60±014 mg/dl, 0 40±0 27 mg/dl and 75 31±28 59 mg/dl, 0 98±0 13 mg/dl, 0 88±0 47 mg/dl, respectively) (P < 0 05).

Circulating nitric oxide (NO), asymmetric dimethylarginine (ADMA), homocysteine, and oxidative status in obstructive sleep apnea–hypopnea syndrome (OSAHS)

Obstructive sleep apnea–hypopnea syndrome (OSAHS) with episodic hypoxia–reoxygenation is associated with increased cardiovascular morbidity and mortality. Therefore, increased homocysteine, asymmetric dimethylarginine (ADMA), oxidative status, and decreased nitric oxide levels have been implicated as possible mechanisms for development of cardiovascular diseases. We aimed to investigate changes in the levels of these substances in patients with OSAHS in comparison with nonapneic controls. Thirty-four OSAHS patients and 15 healthy controls were included in this study. In the blood samples, oxidative status and nitric oxide levels were measured with spectrophotometric methods. Plasma ADMA and homocysteine levels were determined by using high-performance liquid chromatography with fluorescence detection. Nitric oxide levels were significantly low in OSAHS patients (p < 0.05) and correlated with mean SaO2 (r = 0.513, p < 0.002) and lowest SaO2 (r = 0.363, p < 0.03). Oxidative status, ADMA, and homocysteine levels were higher in OSAHS patients, but difference did not reach statistical significance. After dividing patients into moderate (AHI = 5–29) and severe (AHI ≥ 30) OSAHS groups, significantly increased homocysteine levels were observed in the severe OSAHS group (p < 0.05). Nitric oxide levels negatively correlated with oxidative status in total OSAHS patients (r = −0.415, p < 0.02) and also in severe OSAHS group (r = −0.641, p < 0.007). Hyperhomocysteinemia and diminished NO production may be causal factors in endothelial dysfunction seen in OSAHS and may explain the association between OSAHS and cardiovascular diseases. These modifiable factors should be monitored in patients suspected of having OSAHS.

Serum uric acid levels in cardiovascular diseases

Objective: Comparison of the serum uric acid levels of healthy people ( n=71) and patients with cardiovascular diseases (CVD) (n=62). Subjects and methods: The patients included had either experienced acute myocardial infarction (AMI) ( n=31), atherosclerosis (AT) (n=23) or ischaemia ( n=8). The mean values (x±SD) of serum uric acid levels of the control group, the patients with CVD as a whole, and patients with AMI, AT and ischaemia were 4·15±0·45 mg%, 5·6±2·06 mg%, 5·96±2·60 mg%, 5·38±1·22 mg% and 4·94±1·40 mg%, respectively. A statistically higher level of serum uric acid was found in the controls compared to the CVD patients ( P < 0·05). Conclusion: The higher serum uric acid levels found in CVD patients suggests that any protective antioxidant effect which uric acid has is overwhelmed by other negative effects on pathogenesis.

Increased levels of 8-hydroxydeoxyguanosine and its relationship with lipid peroxidation and antioxidant vitamins in lung cancer

Abstract Background: Reactive oxygen species produced either endogenously or exogenously can attack lipids, proteins and DNA in human cells and cause potentially deleterious consequences. In recent years, their role in the pathogenesis of lung cancer and the preventive effect of antioxidants have been studied extensively. In this study, our aim was to investigate the levels of 8-hydroxy-2′-deoxyguanosine (8OHdG) and malondialdehyde as a marker for the effects of reactive oxygen species on DNA and lipids, the levels of antioxidant vitamins and the correlations between these oxidative stress markers and antioxidants in lung cancer. Methods: Serum malondialdehyde, β-carotene, retinol, and vitamins C and E were measured by high-performance liquid chromatography methods in fasting blood samples and 8OHdG was measured by gas chromatography-mass spectrometry in 24-h urine samples of patients with lung cancer (n=39) and healthy controls (n=31). Results: The levels of 8OHdG and malondialdehyde were significantly higher (p<0.05 and p<0.005, respectively) and β-carotene, retinol, and vitamins C and E (p<0.0001, p<0.0001, p<0.0001, and p<0.05, respectively) were significantly lower in patients than in controls. There was a significantly positive correlation between 8OHdG and malondialdehyde (r=0.463, p=0.01) and a negative correlation between the levels of 8OHdG and retinol (r=–0.419, p=0.021) in the patient group. Conclusions: Our results demonstrate that the oxidant/antioxidant balance was spoiled in favor of lipid peroxidation and DNA damage in lung cancer patients. Significant increases in the levels of malondialdehyde and 8OHdG and decreases in the levels of antioxidants suggest the possible involvement of oxidative stress in lung cancer. Clin Chem Lab Med 2008;46:107–12.

Ascorbic acid and uric acid levels in lung cancer patients

Objective: To study any possible association between serum ascorbic acid and uric acid levels with lung cancer.

Oxidative stress in patients with essential hypertension: A comparison of dippers and non-dippers

BACKGROUND Oxidative stress seems to play an important role in the pathophysiology of essential hypertension. We aimed to examine serum MDA, NO, 8-OHdG, ADMA, NT, CoQ10 and TAC as biomarkers of oxidative stress in dipper and non-dipper hypertensive patients. METHODS Eighteen dipper hypertensives, 20 non-dipper hypertensives and 22 healthy control subjects were included in the study. Clinical assessment and ambulatory blood pressure monitoring were performed in patients. Serum MDA, TAC and NO levels were measured by using spectrophotometric methods. CoQ10 levels were measured by HPLC method. 8-OHdG, ADMA and NT were quantitated by ELISA methods. RESULTS MDA levels were significantly higher in dipper and non-dipper groups compared to controls (p<0.05 and p<0.01, respectively). TAC levels were found at low level in patients dipper and non-dipper patients compared to control group (p<0.01). Higher ADMA and NT levels but lower CoQ10 levels were found in non-dipper group compared to healthy controls (p<0.01, p<0.05, and p<0.05, respectively). ADMA levels were found higher in non-dipper group than those of dipper group (p<0.01). DISCUSSION Increased ADMA, NT levels and decreased CoQ10 levels in non-dipper hypertensive patients might indicate more severe oxidative stres compared with dipper hypertensive patients, which plays an important role in the development of cardiovascular diseases. Increased MDA and reduced TAC levels might be considered as prospective prognostic markers of the development of cardiovascular diseases in dipper and non-dipper hypertensive patients.

Increased oxidative DNA damage and impaired antioxidant defense system in patients with gastrointestinal cancer

BACKGROUND Highly active intermediates are formed in aerobic metabolism which in turn leads to cellular damage. It is increasingly proposed that free radicals play a key role in human cancer development. The aim of this study was to investigate changes in 8-hydroxy-deoxyguanosine, nitrite+nitrate, total glutathione, total antioxidant capacity levels and superoxide dismutase, catalase, glutathione peroxidase activities in operative patients with gastrointestinal cancer before and after surgery and compare with inoperative patients. METHODS Oxidative stress parameters were measured in 59 gastrointestinal cancer patients and 20 controls. 8-hydroxy-deoxyguanosine was quantitated by Elisa method. Superoxide dismutase, catalase, glutathione peroxidase were assayed with colorimetric methods; Nitrite+nitrate, total glutathione and total antioxidant capacity were assayed with spectrophotometric methods. RESULTS 8-hydroxy-deoxyguanosine levels in cancer patients were higher than those of control group (p<0.01). Similarly, glutathione levels were increased compared with controls (p<0.01). However, nitrite+nitrate, total antioxidant capacity levels and superoxide dismutase and catalase activities were decreased in cancer patients compared with controls (p<0.01, p<0.01, p<0.05, p<0.01, respectively). The patients were divided into two groups; operative (n = 30) and inoperative (n = 29). A significant difference was found in inoperative group compared with postoperative group according to glutathione peroxidase activity (p<0.05). DISCUSSION Our results demonstrate that the oxidant/antioxidant balance was altered in favor of free radicals and DNA damage in gastrointestinal cancer patients. Significant increases in 8-hydroxy-deoxyguanosine, glutathione and decreases in nitrite+nitrate, SOD, CAT activities and antioxidant molecules suggest the possible involvement of oxidative stress in gastrointestinal cancer. Glutathione peroxidase activities in postoperative patients were higher compared to inoperative patients.