Caloric restriction improves the redox homeostasis in the aging male rat heart even when started in middle-adulthood and when the body weight is stable.

Evidence indicates that maintenance of redox homeostasis is fundamental for cellular longevity. Caloric-restriction (CR) is said to decrease the formation of oxidatively modified cellular macromolecules and improve health. On the other hand, some studies indicate that many CR studies are flawed, because ad libitum fed rats are not well-controlled. Thus, it is claimed that purported beneficial effects of CR could be not due to real CR effect, but due to control animals going obese. Also, it remains to be elucidated whether effects of CR could be observed even when CR is started in mid-adulthood. Male Sprague-Dawley rats were grouped as: non-CR 6-month-old rats (n = 7), 24-month-old rats subjected to 40% CR for 6 months between 18th and 24th months (n = 8), and non-CR 24-month-old animals (n = 8). We investigated 16 previously validated biomarkers of macromolecular redox homeostasis, ranging from protein and lipid oxidation to glycation and antioxidative capacity. In the present study, the protein, lipid and antioxidant capacity redox homeostasis biomarkers overwhelmingly indicate that, CR, even though not started very early in adulthood, could still offer potential therapeutic effects and it could significantly improve various redox homeostasis biomarkers associated with disease reliably in the heart tissue of aging male Sprague-Dawley rats. Therefore, the effects of CR likely operate through similar mechanisms throughout adulthood and CR seems to have real ameliorative effects on organisms that are not due to confounding factors that come from ad libitum fed rats.

Relation between Endothelial Nitric Oxide Synthase Genotypes and Oxidative Stress Markers in Larynx Cancer.

Nitric oxide synthase (eNOS/NOS3) is responsible for the endothelial synthesis of nitric oxide (NO(•)). G894T polymorphism leads to the amino acid substitution from Glu298Asp that causes lower NOS3 activity and basal NO(•) production in NOS3 894T (298Asp) allele carriers compared with the GG homozygotes. NO(•) acts as an antioxidant protecting against Fenton's reaction which generates highly reactive hydroxyl radicals. Allelic variation of NOS3 may influence an individual's risk of laryngeal cancer (LC). In the current study we have examined the possible relationship between NOS3 G894T genotypes and various systemic oxidative damage markers such as protein carbonyl, advanced oxidation protein products, Cu, Zn-superoxide dismutase, thiol group fractions, and lipid hydroperoxides in LC patients. Genotyping was carried out by PCR-RFLP. In LC patients with TT genotype, Cu, Zn-superoxide dismutase activities and nonprotein thiol levels were significantly higher than the controls. In patients with GT and GG genotype, high levels of lipid hydroperoxides showed statistical significance when compared to controls. Our results indicate a potential relationship among G894T polymorphism of NOS3, and impaired redox homeostasis. Further studies are required to determine the role of NOS3 gene polymorphism and impaired plasma redox homeostasis.

Effects of estrogens on oxidative protein damage in plasma and tissues in ovariectomised rats.

PURPOSE: To assess estrogen-related changes in the redox status of the brain and liver proteins as well as the systemic oxidative stress in ovarectomised (OVX) rats METHODS: Twelve-week-old, sexually mature female Sprague-Dawley rats (200-250g) were randomly divided into four groups: The following treatment combinations were administrated daily to all in 0.05 ml 96% ethanol solution by gastric gavage. (1) Sham operation (2) OVX rats (3) OVX rats [0.02 mg/kg/day of 17beta-estradiol (E2) and 0.01 mg/kg/day of norethisterone acetate] (4) OVX rats [E2 (0.01 mg/kg/day) and drospirenon (0.02 mg/kg/day)]. Estrogen levels were determined using routine clinical-chemistry methods. We also measured protein oxidation parameters such as protein carbonyl (PCO), total thiol (T-SH) and the other oxidative stress markers malondialdehyde (MDA) and glutathione (GSH). RESULTS: Ovariectomy resulted in abnormal elevation of plasma and tissue oxidative stress markers and changes in redox status of the proteins in tissue dependent manner. Supplementation of various estrogens combinations partially alleviated these abnormalities and restored redox homeostasis of proteins after the ovariectomy. Among the studied protein oxidation parameters, plasma and tissue PCO levels of the OVX rats were higher than those of the control groups (P < 0.01). Hormone replacement therapies (HRT) caused a decrease in PCO and MDA in both plasma and tissue of the OVX rats (P < 0.01). HRT in OVX rats decreased plasma MDA and increased liver and brain GSH (P < 0.01). Liver MDA levels of the Drospirenon-treated rats were lower than in the norethisterone acetate group (P < 0.01). On the other hand, Drospirenon increases brain GSH s more effectively than norethisterone acetate (P < 0.01). After bilateral oopherectomy, plasma and tissue T-SH levels decreased in the OVX group compared with control (P < 0.01). Norethisterone acetate increased plasma T-SH more effectively than Drospirenon (P < 0.05) CONCLUSIONS: The study showed the extent of oxidative protein damage (OPD) in this model of estrogen deficiency. The protective effect of estrogens against tissue specific OPD suggests that estrogens play an important role within the antioxidant defense systems in plasma, liver and brain. The exact molecular mechanisms leading to these findings are not yet completely known. Meanwhile, hormone replacement therapy for the prevention of OPD in a tissue specific manner may be required.

Protein oxidation parameters in type 2 diabetic patients with good and poor glycaemic control.

AIM: In order to examine the influence of oxidative stress on protein oxidation, type 2 diabetic patients without clinical evidence of complications, either in good or poor glycaemic control, were studied. METHODS: Plasma protein carbonyl (PCO), total thiol (T-SH), and advanced oxidation protein products (AOPP) levels as markers of protein oxidation, and lipid hydroperoxide (LHP) levels as markers of lipid peroxidation were determined. Glycated haemoglobin (HbA1c) levels were used as an index of glycaemic control. The subjects were divided into two groups according to their HbA1c level at inclusion as follows: good HbA1c<=7%, and poor HbA1c > 7%. RESULTS: Plasma PCO and AOPP levels of diabetic patients with poor glycaemic control were increased significantly compared with those of the diabetic patients with good glycaemic control. The decreased plasma T-SH level in the diabetic patients with poor glycaemic control was not statistically significant. On the other hand, plasma LHP levels were increased significantly in the diabetic patients with poor GC compared with those of the diabetic patients with good glycaemic control. CONCLUSION: This study supports the hypothesis that poor glycaemic control is an important factor in generation of increased protein oxidation in type 2 diabetic patients clinically free of complications. Increase in plasma PCO, AOPP, and LHP levels in the diabetic patients with poor glycaemic control may contribute to the development of diabetic complications.

Oxidative protein damage parameters in plasma in chronic experimental diabetes in rats.

An increase in oxidative stress may contribute to the development of oxidative protein damage (OPD) in the streptozotocin-diabetic rat. To show the effect of hyperglycemia in promoting OPD, we determined protein carbonyl (PCO), nitrotyrosine (NT), total thiol (T-SH) and advanced oxidation protein product (AOPP) levels as markers of OPD, and lipid hydroperoxide (LHP) levels as a marker of lipid peroxidation in plasma of acute and chronic diabetic male Sprague-Dawley rats and their controls. The levels of the studied markers, except NT, were determined by colorimetric methods. NT levels were measured by ELISA. Plasma PCO and AOPP levels of chronic diabetic rats were increased significantly compared with those of both acute diabetic rats and the controls. Plasma NT levels of the three groups were not different. Plasma T-SH levels of acute diabetics were increased significantly compared with those of the controls while T-SH increase in the chronic diabetics was not significant. Plasma LHP levels were increased significantly in the chronic diabetic rats compared with those of the controls. The increase in plasma PCO, AOPP, LHP levels in chronic but not in acute diabetic rats may be indicating that persistence of hyperglycemia is involved in the evolution of OPD while plasma NT levels do not seem to reflect OPD in diabetes.

Determination of oxidative protein and lipid damage in adult hypopituitary patients with GH deficiency.

The aim of this study is to determine oxidative protein and lipid damage in adult hypopituitary GH-deficient patients. Eighteen hypopituitary GH-deficient--otherwise healthy-adults on conventional replacement therapy other than GH (9 male, 9 female, age 41.8 +/- 16.4 yr) and 18 healthy subjects (6 male, 12 female, age 40.3 +/- 16.2 yr) participated in the study. Plasma products of oxidative protein damage [protein carbonyl (PCO) and nitrotyrozine (NT)], plasma oxidized LDL (oxLDL), plasma product of oxidative lipid damage [lipid hydroperoxide (LHP)] and antioxidant status of the plasma [total thiol (T-SH)] were measured. Body fat percentage, total and LDL-cholesterol concentrations were significantly higher in the hypopituitary group. Plasma PCO, NT, LHP and T-SH concentrations did not differ significantly between patients and controls. OxLDL concentration was significantly higher in the hypopituitary patients (62.4 +/- 17.8 vs 43.1 +/- 11.3 U/l, p = 0.001). In the patients, oxLDL correlated significantly with the duration of hypopituitarism (r = 0.6323, p = 0.01). In the controls, oxLDL correlated significantly with blood pressure, total and VLDL-cholesterol concentrations. Increased oxLDL concentration may indicate increased oxidative stress within the vascular compartment and may contribute to the proatherogenic state in GH-deficient hypopituitary patients independent from conventional risk factors.

Relation of oxidative protein damage and nitrotyrosine levels in the aging rat brain.

An increase in oxidative stress may contribute to the development of oxidative protein damage in the aging rat brain. In the present study, we investigated the relation between nitrotyrosine levels and other oxidative protein damage parameters such as protein carbonyl and protein thiol, as well as oxidative stress parameters such as total thiol, nonprotein thiol, and lipid hydroperoxides in the brain tissue of young, adult, and old Wistar rats. Brain nitrotyrosine levels of old rats were significantly decreased compared with those of young rats. Young and adult rats were not significantly different as far as these parameters were concerned, however, brain protein carbonyl and lipid hydroperoxide levels of old rats were significantly increased compared with those of young and adult rats. On the other hand, brain tissue total thiol, nonprotein thiol, and protein thiol levels of old rats were significantly decreased compared with those of young and adult rats. The strong correlation we found between protein carbonyl and lipid hydroperoxide levels indicates a striking relation between protein oxidation and lipid peroxidation in the aging brain tissue. The results of this study suggest that protein carbonyl formation is both a sensitive and a specific marker of brain aging. However, decreased nitrotyrosine levels in old rats, in contradiction to the expected, may be due to mechanisms other than oxidative protein damage in the aging rat brain.

Antibodies against oxidised low-density lipoprotein in hypopituitary patients with growth hormone deficiency.

Growth hormone-deficient hypopituitary patients on conventional replacement therapy have increased mortality and morbidity from atherosclerotic cardiovascular disease. Oxidation of low-density lipoprotein (LDL) is a key event in the development and progression of atherosclerosis. Antibodies against oxidatively modified LDL may reflect in vivo oxidation processes. The aim of this study is to determine the effect of growth hormone deficiency on oxidised-LDL antibody titres in panhypopituitary patients taking conventional replacement therapy. Twenty-one GH deficient, adult panhypopituitary patients and 17 age, sex and body mass index-matched healthy controls were studied. After an overnight fast, anthropometric parameters were measured and body composition was determined by a bioelectrical impedance analyser. Venous blood samples were obtained for the measurements of biochemical parameters. Antibodies to oxidised-LDL were analysed by an ELISA system in the patients' and controls' serum. No significant difference was observed between the oxidised-LDL antibody titres in hypopituitary patients and controls (395.4+/- 183.2 mU/ml and 393.2 +/- 186.2 mU/ml respectively, p = NS). A significant positive correlation was observed between oxidised-LDL antibody titres and total cholesterol concentrations in the patients (r = 0.449, p < 0.05). No significant correlation was observed between oxidised-LDL antibody titres and anthropometric/biochemical variables in the controls. It is concluded that relatively increased LDL oxidation may not contribute to the progression of atherosclerosis in hypopituitary patients.

Oxidative protein damage in early stage Type 1 diabetic patients.

To examine the influence of oxidative stress on oxidative protein damage, we studied 51 young Type 1 diabetic patients clinically free of complications and 48 healthy normolipidaemic age-matched controls. We determined: (1) plasma carbonyl (PCO), plasma total thiol (T-SH), and nitrotyrosine (NT) levels as markers of oxidative protein damage; (2) plasma lipid hydroperoxide (LHP), and nitric oxide (NO) levels as markers of oxidative stress; (3) plasma total antioxidant capacity (TAO), ceruloplasmin (Cp), transferrin (TRF), unsaturated iron binding capacity (UIBC), erythrocyte glutathione (GSH), and erythrocyte superoxide dismutase (SOD) as markers of free radical scavengers. There were no significant differences in the levels of these markers between prepubertal diabetic patients and the controls. The levels of both of PCO and LHP were increased in adolescent and young adult Type 1 diabetic patients with respect to their controls. In the adolescent group, patient versus control values for PCO were 1.04+/-0.067 versus 0.67+/-0.0274 nmol/mg and for LHP they were 2. 10+/-1.09 versus 1.00+/-0.4 nmol/mg. In the young adult group, patient versus control values for PCO were 0.99+/-0.054 versus 0. 66+/-0.02 nmol/mg and for LHP they were 1.96+/-0.78 versus 1.15+/-0. 4 nmol/mg. TAO levels were significantly decreased in adolescent diabetic patients compared to their controls (0.92+/-0.27 vs. 1. 86+/-0.37) and in young adult diabetic patients compared to their controls (0.80+/-0.27 vs. 2.11+/-0.54 nmol/mg). T-SH was not different between diabetic patients and the controls. Serum NT, NO, and erythrocyte SOD levels were not different either between three groups of diabetic patients or between the patients and their controls. We attribute this lack of difference to limited disease duration. Changes in markers of oxidative stress other than NT, NO, and SOD observed in adolescent and young adult early stage Type 1 diabetic patients contribute to the imbalance in the redox status of the plasma. We attribute this imbalance to metal-catalyzed protein oxidation in both groups of Type 1 diabetic patients clinically free from complications.

Oxidative protein damage in type I diabetic patients with and without complications.

To examine the influence of oxidative stress on oxidative protein damage, we studied 47 Type I diabetic patients with and without complications. We determined plasma protein carbonyl, plasma protein thiol and nitrotyrosine levels as markers of oxidative protein damage, plasma lipid hydroperoxide levels as markers of oxidative stress, and plasma total thiol, plasma nonprotein thiol, erythrocyte glutathione, plasma ceruloplasmin, transferrin and total iron binding capacity as markers of free radical scavenging. There were no significant differences in nitrotyrosine, total plasma thiol, protein thiol, and erythrocyte glutathione levels between diabetic patients with complications and without complications. However, plasma protein carbonyl, lipid hydroperoxide, and nonprotein thiol levels were significantly increased in diabetic patients with complications compared with diabetic patients without complications. Although redox status of plasma is impaired in diabetic patients, we suppose these significantly different markers reflect enhanced oxidative protein damage in diabetic patients with complications.