Comparison of oxidative stress indicators in plasma of recent-onset and long-term type 1 diabetic patients

Oxidative stress was compared in plasma of 15 recently diagnosed (5 yr) type 1 diabetic patients with 15 healthy volunteers. Lipid peroxidation indices measured in plasma included thiobarbituric acid-reactive substances (TBARS), conjugated dienes, and lipid hydroperoxide (ROOH). The values obtained were corrected for phospholipid to minimize this as a confounding factor. In recently diagnosed diabetics, plasma conjugated lipid dienes were significantly elevated. However, in long-standing diabetics there was a marked increase in TEARS, conjugated dienes, and lipid hydroperoxide levels. Our findings showed increased oxidative stress in type 7 diabetics regardless of metabolic control and that conjugated diene measurement appeared to be the most sensitive bioindicator of oxidant stress in our population

Hyperuricemia in hypothyroidism: Is it associated with post-insulin infusion glycemic response?

This experimental study was designed to examine whether hyperuricemia in hypothyroidism is associated with insulin resistance. For induction of hypothyroidism, rabbits (n = 12) were administered methimazole orally (75 mg/100 g food) for 30 days. T-3, T-4 and TSH values measured in plasma prior to and at the end of the experimentation period revealed the establishment of hypothyroidism. In the euthyroid and hypothyroid states of rabbits, crystalline porcine insulin was administered (0.1 unit/kg body weight) intraperitoneally and plasma glucose was measured at 0, 15, 30, 45 and 60 minutes. Sum of post insulin infusion glucose values was considered to reflect insulin resistance. Creatinine clearance (GFR) and uric acid clearance (C-uA) were determined. Additionally, triglycerides were measured in plasma and Mg2+ both in erythrocytes and in plasma. Due to hypothyroidism: i) The glycemic response to insulin was not altered. ii) GFR and C-uA were both decreased but C-uA/GFR unchanged. iii) Triglycerides in plasma decreased. iv) Mg2+ concentration increased in plasma whereas decreased in erythrocytes. Several associations were observed between the variables on correlation analysis. On the basis of our data, it could be suggested that insulin resistance does not exist in hypothyroidism. Hyperuricemia observed in hypothyroidism should be considered to be secondary to decreased renal excretion but not as an indicator of insulin resistance. (C) 2003 Tohoku University Medical Press

The effects of energy restricted diet on the activities of plasma Cu-ZnSOD, GSH-Px, CAT and TBARS concentrations in late pregnant ewes

The aim of the study was to determine the effects of low energy diets on the enzymatic antioxidant activities of ewes in late pregnancy. Thirty Chios ewes were used. Twenty pregnant ewes were divided into 2 groups of 10 ewes each (groups II and III), with 10 non-pregnant ewes being separated into a third group (group I). The ewes in groups I, II and III were fed rations containing 9.14 MJ ME/kg of dry matter (DM)-10.23% crude protein (CP), 10.20 MJ ME/kg of DM-15.04% CP, and 8.82 MJ ME/kg of DM-14.47% CP, respectively. Plasma copper-zinc superoxide dismutase (Cu-Zn SOD), glutathione peroxiclase (GSH-Px), catalase (CAT) activities and thiobarbituric acid reactive substances (TBARS) concentrations were measured on days 105 and 148 of pregnancy. No significant differences for Cu-Zn SOD and TBARS were detected among the groups on days 105 and 148 of pregnancy. The catalase activities of group III were higher by P < 0.05 than those of both groups I and II on day 148 of pregnancy. The GSH-Px activities of group II were higher than those of group I on day 148 of pregnancy (P < 0.05). In a 2-day comparison of each group, only GSH-Px activities increased in group [if (P < 0.05). It was concluded that the reason for the high plasma CAT and GSH-Px activities at the end of pregnancy is to protect the foetus from the deleterious effects of hydrogen peroxide

Biochemical evaluation of oxidative stress in propylthiouracil treated hyperthyroid patients. Effects of vitamin c supplementation

In this study the impact of vitamin C supplementation on oxidative damage as assessed by thiobarbituric acid reactive substances and markers of antioxidant status: namely Cu/Zn superoxide dismutase, glutathione peroxidase, glutathione reductase and glutathione were investigated in 24 hyper-thyroid patients under propylthiouracil therapy (3x100 mg/day) for five days and in 15 healthy controls. Ascorbic acid (1000 mg/day) was given as a supplement for 1 month to both the patients and controls during the study period. Heparinised blood samples were taken at the beginning and the end of one month ascorbic acid supplementation

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 (p0.05), oxLDL Ab (p0.05), LDL cholesterol (LDL-Chol) (p0.05), total cholesterol (p0.05) and lower HDL-Chol (p0.05). OxLDL was found to be positively correlated with total cholesterol (r=0.471, p0.05) and LDL-Chol (r=0.614, p0.01) and GRAS (r=0.435, p0.05) and negatively with HDL-Chol (r=-0.459, p0.05), 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 stress in heart tissue of hyperthyroid and iron supplemented rats

This study was designed to investigate the effect of hyperthyroidism and/or iron supplementation on cardiac oxidative stress parameters-the lipid peroxidation end product glutathione (GSH), glutathione peroxidase (GSH-Px), and superoxide dismutase (CuZnSOD) - in rats, In plasma, ferritin as an indicator of iron status and glutamate oxaloacetate transaminase (GOT) as an indicator of damage to the heart tissue were analyzed. Our findings show that hyperthyroidism increased lipooxidative damage as reflected by higher lipid peroxidation end product levels and elevated antioxidant defense parameters-GSH and GSH-Px. Iron supplementation per se does not affect oxidative stress parameters studied in the euthyroid state. Although iron increased lipid peroxidation in the hyperthyroid state, this effect was less than that seen in euthyroidism. Iron supplementation to hyperthyroid rats significantly lowered plasma ferritin levels, suggesting increased iron elimination with consequently reduced oxidative stress

Evaluation of oxidative stress in experimental colitis: Effects of L-arginine-nitric oxide pathway manipulation

In this study it was of interest to evaluate the impact of nitric oxide (NO) modulation by administration of arginine/NAME, on oxidative stress in experimental colitis induced by 2, 4, 6-trinitrobenzenesulfonic acid. Arginine was used to increase NO levels while NAME lowered oxidant levels. Histopathological findings of colon revealed mucosal inflammation in all groups but significantly higher with arginine alone. The levels of NO and of thiobarbituric acid-reactive substances (TBARS, a marker of lipid peroxidation) were observed to be significantly higher in the arginine-administered group compared to glycine, and these levels were found to decrease on administration of NAME to both glycine- and L-arginine-administered groups. Glutathione peroxidase (GSH-Px) activity and glutathione (GSH) levels were significantly higher in arginine administered group compared to glycine. Significantly higher CuZn superoxide dismutase (CuZn-SOD) activity was observed in the L-arginine + L-NAME group compared to arginine. Data show that NO plays a role in oxidant damage found in experimental colitis and that the use of NAME may potentially inhibit injury

Laryngeal cancer: in relation to oxidative stress

This study was designed to investigate the oxidative stress parameters in laryngeal cancer and cancer-free adjacent tissues. Lipid peroxidation end product and the endogenous antioxidant components-CuZn superoxide dismutase (CuZnSOD) glutathione peroxidase (GSH Px), glutathione reductase (GSSG Rd) and glutathione (GSH)-were analysed by spectrophotometric and kinetic methods. Laryngeal cancer tissue exhibited higher lipid peroxidation than cancer free adjacent tissue. CuZn SOD and GSH Px activities and GSH level were significantly higher and GSSG Rd activity significantly lower in the cancer tissue. Detection of the antioxidant status may be useful to determine the tumour resistance to therapy, to choose the correct radiotherapy/chemotherapy and to monitor the effectiveness of the therapetic strategy

Plasma AGE-peptides and C-peptide in early-stage diabetic nephropathy patients on thiamine and pyridoxine therapy

Aim. The aim of the study was to evaluate circulatory AGE-peptide levels in diabetic nephropathy and to observe the effects of thiamine (vitamin B1) and pyridoxine (vitamin B6) therapy

Influence of propylthiouracil treatment on oxidative stress and nitric oxide in Basedow disease patients

Oxidative stress parameters and nitric oxide (NO) values were determined in 27 newly diagnosed Basedow patients before and afer 1 mo of propylthiouracil (PTU) therapy and in 15 healthy controls. Basedow patients exhibited increased triiodothyronine (T-3) and thyroxine (T-4) and decreased thyroid-stimulating hormone (TSH) values compared to controls. Significantly higher thiobarbituric acid-reactive substances (TBARS), NO and glutathione (GSH) levels, and CuZn superoxide dismutase (CuZn SOD) activity were found in Basedow patients in comparison to controls, regardless of sex. Treatment with PTU (3 x 100 mg/d for 30 d) was effective in decreasing T-3 and T-4 and increasing TSH levels. Significantly decreased NO and TBARS and increased GSH and CuZn SOD levels were observed in PTU-treated Basedow patients compared to pre-PTU administration. PTU-treated patients compared to controls still exhibited significantly higher T-3 and lower TSH values and higher NO, TBARS, GSH, and CuZn SOD levels. The induced antioxidant defense and decrease in NO values in response to PTU therapy emphasizes the role of PTU as an antithyroid drug, where the ability to diminish hyperthyroidism results in decreased catabolism and lower oxidant generation