Melatonin reduces oxidative stress in erythrocytes and plasma of senescence-accelerated mice

It has been suggested that oxidative stress is a feature of aging. The goal of the present study was to assess the oxidant effects related to aging and the protective role of exogenous melatonin in senescence-accelerated mice (SAMP8). Two groups of SAMP8 mice (males and females) were compared with their respective control groups of SAMR1 mice (senescence-resistant inbred strain) to determine their oxidative status without melatonin treatment. Four other groups of the same characteristics were treated with melatonin (10 mg/kg/day) in their drinking water. The melatonin concentration in the feeding bottles was titrated according to water consumption and body weight (i.e. 0.06 mg/mL for 30 g of body weight and 5 mL/day of water consumption). The treatment began when animals were 1-month old and continued for 9 months. When mice were 10-month old, they were anesthetized and blood was obtained. Plasma and erythrocytes were processed to examine oxidative stress markers: reduced glutathione (GSH), oxidized glutathione (GSSG), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR), glutathione S-transferase (GST), thiobarbituric acid reactive substances (TBARS), and hemolysis. The results showed greater oxidative stress in SAMP8 than in SAMR1, largely because of a decrease in GSH levels and to an increase in GSSG and TBARS with the subsequent induction of the antioxidant enzymes GPX and GR. Melatonin, as an antioxidant molecule, improved the glutathione-related parameters, prevented the induction of GPX in senescent groups, and promoted a decrease in SOD and TBARS in almost all the groups.     

Antioxidant status of erythrocytes from patients with cirrhosis.

BACKGROUND/AIMS: The aim of the present study was to investigate possible involvement of oxidant stress in the anemia of cirrhotic patients and to assess blood antioxidant status of these patients. METHODOLOGY: Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) enzyme activities were measured in the erythroctes from patients with liver cirrhosis and from controls. Levels of thiobarbituric acid reagent substance were also measured in the erythrocyte (TBARSe) and plasma (TBARSp) samples of the groups. RESULTS: Lower activities of SOD and GSH-Px were established in the erythrocytes from patients compared with control subjects. No differences were found between erythrocyte TBARS levels of control and patient groups. Plasma TBARS levels were, however, found to be significantly higher in the patient groups compared with controls. CONCLUSIONS: Results suggest that although enzymatic antioxidant defense system is significantly reduced in the erythrocytes from cirrhotic patients, this does not lead to further peroxidative reactions in the erythrocytes, possible due to preoxidation of some cellular structures sensitive to peroxidative attacks. There was, however, an important indication of accelerated peroxidative reactions in the plasma of the cirrhotic patients, which possibly resulted from extracellular oxidant stress in these patients.     

Antioxidant supplementation attenuates oxidative stress in chronic hepatitis C patients

Reactive oxygen species (ROS) overgeneration is involved in the pathogenesis of hepatitis C. The aim of this study was to evaluate the antioxidant status in the blood of HCV infected patients treated or not with standard therapy before and after supplementation of vitamins E, C and zinc. Biomarkers of oxidative stress were evaluated in the blood of three groups of patients: group 1 - controls; group 2 - HCV patients without treatment examined before and after a daily antioxidant supplementation (vitamin E 800 mg, C 500 mg and zinc 40 mg) for 6 months; and group 3 - HCV patients treated with pegylated interferon combined with ribavirin, also examined before and after the same antioxidant supplementation. Before antiviral treatment HCV patients showed enhanced superoxide dismutase, catalase and glutathione peroxidase activities and decreased glutathione reductase activity, while lipoperoxidation was increased and reduced glutathione showed decreased levels compared to controls. Treatment with standard therapy enhanced the activities of catalase and glutathione S-transferase, increased contents of protein carbonyl and promoted further reduced glutathione depletion. After antioxidant supplementation, decreased catalase and glutathione S-transferase activities, decreased lipoperoxidation in group 2, and increased reduced glutathione contents in both supplemented groups were detected. Before antioxidant supplementation, alanine aminotransferase and gamma glutamyl transferase contents showed significant increases in group 2. CONCLUSION: Untreated HCV patients and also those treated with the standard therapy are coping with a systemic oxidative stress. The antioxidant supplementation conferred an antioxidant protection to both supplemented groups attenuating oxidation processes related to the disease.     

Effect of melatonin on the oxidative stress in erythrocytes of healthy young and elderly subjects

The disturbances in pro- and antioxidant balance may play an important role in the pathomechanism of aging. The pineal hormone melatonin, which exerts effective antioxidative properties, is suggested to be involved in the aging process. The aim of this study was to compare the oxidative stress in erythrocytes of healthy young adults and elderly people, and to determine the influence of melatonin supplementation on measured parameters in both examined groups. The malondialdehyde (MDA) and reduced glutathione levels as well as Cu-Zn superoxide dismutase (SOD-1), catalase, glutathione peroxidase (GSH-Px), glutathione S-transferase (GST) and glutathione reductase (GR) activities in erythrocytes and morning serum melatonin concentration in 14 healthy young adults and 14 healthy elderly people at baseline and after the 30th day of melatonin (5 mg daily) supplementation were determined. A significant age effect on increasing the MDA level and decreasing SOD-1, GSH-Px and GR activities as well as melatonin concentration was observed. Melatonin supplementation resulted in a significant increase in melatonin concentration, SOD-1 and GR activities and a decrease in the MDA level in both examined groups. These data indicate an age-related augmentation of oxidative stress in erythrocytes and the improvement of erythrocytic antioxidative defense by melatonin administration. These results might suggest melatonin supplementation to prevent age-related diseases and to prolong the lifespan and improve the quality of life of elderly people.     

Elevated protein carbonyls as plasma markers of oxidative stress in acute pancreatitis

Background: Experimental studies have demonstrated that protein and lipid oxidation is a feature of acute pancreatitis and that antioxidant pretreatment can ameliorate the severity of the disease. Justification for a clinical trial of antioxidant therapy requires stronger evidence for oxidative stress in patients. Aims: To determine if oxidative stress is evident in patients with acute pancreatitis on admission to hospital, if it increases after admission and if it is related to disease severity. Methods: Measurement of plasma concentrations of protein carbonyls and malondialdehyde as markers of protein oxidation and lipid peroxidation, respectively, in a consecutive series of 85 patients with acute pancreatitis 0, 2 and 5 days after admission. Results: Patients with acute pancreatitis had significantly increased concentrations of protein carbonyls in plasma on recruitment (median 27 h after the onset of symptoms) that persisted over 5 days. Protein carbonyls were higher in severe compared with mild disease (median 0.099 and 0.043 nmol/mg protein, respectively, p = 0.0016). They were higher at day 0 in patients recruited with more established pancreatitis than in those presenting early. No increases in malondialdehyde were seen. Receiver operator characteristic curve analysis demonstrated that protein carbonyls at day 0 were comparable with Creactive protein at predicting pancreatitis severity. Conclusion: Our demonstration of substantial protein oxidation provides further evidence for oxidative stress in patients with severe pancreatitis. Our results suggest that there could be a window for early antioxidant intervention and that protein carbonyls could be a useful plasma marker of oxidative injury.     

Breath markers of oxidative stress in patients with unstable angina

Cardiac chest pain is accompanied by oxidative stress, which generates alkanes and other volatile organic compounds (VOCs). These VOCs are excreted in the breath and could potentially provide a rational diagnostic marker of disease. The breath methylated alkane contour (BMAC), a 3-dimensional surface plot of C4-C20 alkanes and monomethylated alkanes, provides a comprehensive set of markers of oxidative stress. In this pilot study, we compared BMACs in patients with unstable angina pectoris and in healthy volunteers. Breath VOCs were analyzed in 30 patients with unstable angina confirmed by coronary angiography and in 38 age-matched healthy volunteers with no known history of heart disease (mean age +/- SD, 62.7 +/- 12.3 years and 62.5 +/- 10.0, not significant). BMACs in both groups were compared to identify the combination of VOCs that provided the best discrimination between the 2 groups. Forward stepwise entry discriminant analysis selected 8 VOCs to construct a predictive model that correctly classified unstable angina patients with sensitivity of 90% (27 of 30) and specificity of 73.7% (28 of 38). On cross-validation, sensitivity was 83.3% (25 of 30) and specificity was 71.1% (27 of 38). We conclude that the breath test distinguished between patients with unstable angina and healthy control subjects.     

Gastric mucosal defences in the elderly.

BACKGROUND: Elderly subjects are more prone to develop gastric injury, but human data on the state of mucosal protective mechanisms are scarce. The aim of the study was to assess gastric mucus and bicarbonate secretion as well as local microcirculation in elderly patients. METHODS: Fasting gastric juice was collected in 45 elderly patients and in 45 control subjects devoid of endoscopic gastric abnormalities. Total mucoproteins, 'mucoprotective index' (as qualitative expression of mucus secretion) and gastric bicarbonate (Feldman's method) were measured. In addition in 24 elderly patients, and in a matching group of younger subjects, gastric mucosal blood flow was measured by laser Doppler flowmetry. RESULTS: Mucus and bicarbonate production was significantly reduced (p < 0.01) in elderly patients, the quality of mucus secretion being unaltered. Gastric mucosal perfusion was also significantly decreased (p < 0. 01) in aged subjects. CONCLUSION: In the elderly gastric mucosal defences are impaired. This is in keeping with a reduced gastric prostaglandin biosynthesis and may account for the higher susceptibility of the mucosa to damaging agents. The possible role of atrophic gastritis and Helicobacter pylori infection as independent confounding factors remains to be determined.     

Peroxyl-induced oxidative stress in aging erythrocytes of rat

This study aims at determining the possible changes in intracellular calcium (Ca_i²⁺), plasma membrane calcium ATPase (PMCA) activity and phosphatidylserine (PS) along with glutathione (GSH) level in response to an oxidant challenge in vitro. Erythrocytes were isolated on Percoll and incubated with 2, 2′azobis (2-aminopropane) hydrochloride (AAPH) as well as with vitamin C preceding AAPH incubation. Membrane integrity in terms of hemolysis was negatively related to acetylcholine esterase (AChE) activity with the extent of reduction under OS being higher in the old erythrocyte than in the young. A divergent pattern was seen towards lower PMCA and higher (Ca_i²⁺) in the young and old cells. However, the PMCA activity in the stressed young cell was high when pre-treated with vitamin C. PS externalization in the young under OS is perhaps analogous to normal aging, with vitamin C preventing premature death. These findings suggest that young erythrocytes may benefit from vitamin C in therapies addressed towards the mechanisms underlying the reduced effects of OS.     

Xanthine oxidase and lens oxidative stress markers in diabetic and senile cataract patients

Xanthine oxidase (XOD) is a prooxidant enzyme possibly implicated in diabetic lens injury and genesis of senile cataract (SC). We evaluated the impact of diabetes on XOD activity and its relationships with lens oxidative stress markers in patients operated on for SC. Serum and lens XOD activities, lens malondialdehyde (MDA), conjugated dienes, superoxide dismutase (SOD), glutathione peroxidase (GPx) and reduced glutathione (GSH) levels were measured in 62 non-diabetic and 29 diabetic patients operated on for SC. Lens XOD, SOD, GPx and GSH levels were gradually declining, while MDA and serum XOD were increasing with patient's age. Lens XOD activity was positively correlated with conjugated dienes concentration (rho = 0.316; p = 0.003) while being inversely correlated with age (rho = ? 0.371; p < 0.001), indicating that low ocular expression of XOD could be related to lower intensity of oxidative stress and delayed occurrence of SC. When samples were adjusted for confounding factors, serum XOD (p < 0.001), lens XOD (p = 0.003) and conjugated dienes (p = 0.002) were significantly higher in diabetic than in non-diabetic group. Lens SOD and GPx were moderately increased while MDA and GSH were unchanged in diabetic, compared with non-diabetic SC group. Blood HbA_1C concentration was positively correlated with lens XOD (rho = 0.346; p < 0.001) as well as serum XOD activity (rho = 0.485; p < 0.001). These results suggest that poor glycemic control may upregulate systemic and ocular XOD activities contributing to lens oxidative stress and possibly to earlier onset of cataract.     

Alterations in plasma oxidative stress markers after laparoscopic operations of the upper and lower abdomen

The patient's position during laparoscopic surgery can have a clinically relevant effect on lower limb and splanchnic circulation; this factor has not yet been investigated with respect to oxidative stress markers. In order to assess this effect, a prospective clinical trial was designed wherein 2 groups of patients were studied. In group A, 15 patients underwent upper abdominal nonhepatobiliary operations (13 modified Nissen fundoplications and 2 Taylor vagotomies) in the head-up position. In group B, 15 patients underwent lower abdominal operations (10 laparoscopic colectomies and 5 inguinal hernia repairs) in the head-down position. The pneumoperitoneum was maintained at 14 mm Hg in all cases. Plasma concentrations of thiobarbituric-acid reactive substances (TBARS), a marker of lipid peroxidation, plasma total antioxidant status (TAS), and serum uric acid concentrations were measured preoperatively, 5 minutes after deflation of the pneumoperitoneum, and 24 hours postoperatively. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) serum activities were measured preoperatively and 24 hours postoperatively. In group A, there was a significant increase in TBARS levels (p<0.005) immediately after deflation of the pneumoperitoneum and a significant decrease in TAS and uric acid levels (p<0.005) in the first postoperative day. There was also a significant postoperative elevation in both ALT and AST activities (p<0.001). In group B, no significant increase was found in postoperative TBARS or transaminase levels. TAS and uric acid levels decreased significantly in the first postoperative day (p<0.05) and (p<0.005, respectively). In conclusion, these results show that a combination of pneumoperitoneum and the head-up position causes significant increase in lipid peroxidation, decrease in plasma TAS, and increase in transaminases. The mechanism responsible for these events could be the low-flow ischemia-reperfusion syndrome induced by the pneumoperitoneum and aggravated by the head-up position.     

Antioxidant vitamins attenuate oxidative stress and cardiac dysfunction in tachycardia-induced cardiomyopathy.

OBJECTIVES: We administered antioxidant vitamins to rabbits with pacing-induced cardiomyopathy to assess whether antioxidant therapy retards the progression of congestive heart failure (CHF). BACKGROUND: Although oxidative stress is increased in CHF, whether progression of heart failure could be prevented or reduced by antioxidants is not known. METHODS: Rabbits with chronic cardiac pacing and sham operation were randomized to receive a combination of beta-carotene, ascorbic acid and alpha-tocopherol, alpha-tocopherol alone or placebo over eight weeks. Echocardiography was used to measure cardiac function weekly. Resting hemodynamics and in vivo myocardial beta-adrenergic responsiveness were studied at week 8. Animals were then sacrificed for measuring myocardial beta-receptor density, norepinephrine (NE) uptake-1 site density, sympathetic neuronal marker profiles, tissue-reduced glutathione/oxidized glutathione (GSH/GSSG) ratio and oxidative damage of mitochondrial DNA (mtDNA). RESULTS: Rapid cardiac pacing increased myocardial oxidative stress as evidenced by reduced myocardial GSH/GSSG ratio and increased oxidized mtDNA and produced cardiac dysfunction, beta-adrenergic subsensitivity, beta-receptor downregulation, diminished sympathetic neurotransmitter profiles and reduced NE uptake-1 carrier density. A combination of antioxidant vitamins reduced the myocardial oxidative stress, attenuated cardiac dysfunction and prevented myocardial beta-receptor downregulation and sympathetic nerve terminal dysfunction. Administration of alpha-tocopherol alone produced similar effects, but the effects were less marked than those produced by the three vitamins together. Vitamins produced no effects in sham-operated animals. CONCLUSIONS: Antioxidant vitamins reduced tissue oxidative stress in CHF and attenuated the associated cardiac dysfunction, beta-receptor downregulation and sympathetic nerve terminal abnormalities. The findings suggest that antioxidant therapy may be efficacious in human CHF.     

Antioxidant activities and oxidative stress byproducts in human hypertension

The objective was to study oxidative status, antioxidant activities, and reactive oxygen species byproducts in whole blood and mononuclear peripherals cells and their relationship with blood pressure. Sixty-six hypertensive patients and 16 normotensive volunteers as a control group were studied. In both, whole blood and peripheral mononuclear cells oxidized/reduced glutathione ratio and malondialdehyde was significantly higher, and the activity of superoxide dismutase, catalase, and glutathione peroxidase was significantly lower in hypertensive patients when compared with normal subjects. The content of damaged base 8-oxo-2'-deoxyguanosine in nuclear and mitochondrial deoxyribonucleoproteins of hypertensive subjects was also significantly higher than that of the normotensive control subjects. No differences in these measurements were found among hypertensive subjects grouped in tertiles of 24-hour average mean blood pressure or between "white-coat" and established hypertensive subjects. Furthermore, no relationship was observed between the average of 24-hour mean blood pressure and oxidized/reduced glutathione ratio, reactive oxygen species byproducts, malondialdehide, or genomic 8-oxo-2'-deoxyguanosine. In whole blood and in mononuclear cells from hypertensive subjects, there was an increase in oxidative stress and a reduction in the activity of antioxidant mechanisms that appeared to be independent of the blood pressure values.     

The biological relevance and measurement of plasma markers of oxidative stress in diabetes and cardiovascular disease

Oxidative stress is associated with many chronic diseases. In this review, we look at the role that oxidative stress may play in diabetes and related cardiovascular disease (CVD) and how oxidative damage may be measured in the plasma. Increased production of reactive oxygen species (ROS) has been implicated in the initiation and progression of both of these conditions and it may be that oxidative stress accounts for the unexplained increase in cardiovascular risk observed in diabetes. Plasma measurements are difficult because of the highly reactive nature of these molecules. Several studies have focused on measuring the total antioxidant buffering capacity of plasma or alternatively specific measures of free radical-mediated damage such as F(2)-isoprostane or oxidised-LDL (Ox-LDL). Perhaps, in the future, the discovery of an 'easy to measure marker' of oxidative stress might be incorporated into risk prediction in diabetes and cardiovascular disease.     

Telomere dysfunction-related serological markers and oxidative stress markers in rheumatoid arthritis patients: correlation with diseases activity

Rheumatoid arthritis (RA) is an inflammatory autoimmune polyarthritis with progressive destruction of the synovial joints associated with systemic manifestations. RA is characterized by infiltration of the synovial joints with inflammatory immune cells with premature immunosenescence. Shorter telomere length in the peripheral blood cells and increase in the oxidative stress have been detected in patients with RA. The aim of the present study was to study the association of markers of telomere shortening and oxidative stress with RA disease activity. Sixty-one RA patients and 15 healthy controls were enrolled in the study. Demographic data, clinical examination, and disease activity status were evaluated for the RA patients. Serum levels of chitinase and NAG (telomere markers) were determined by biochemical reactions using colloidal chitin and NAG as substrates, respectively. Nitric oxide and superoxide dismutase (oxidative stress markers) were determined colometrically and spectrophotometrically, respectively, in the sera of RA patients and controls. Results were correlated with disease activity. Indices of telomere shortening and oxidative markers were significantly higher in RA patients compared to controls. These indices were correlated with signs of disease activity (including number of swollen and tender joints, DAS-28, and inflammatory markers). Rheumatoid arthritis is a disease in which markers of telomere shortening and elevated oxidant stress correlate with disease activity.     

Oxidative stress in erythrocytes from patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation. It has been suggested that the level of reactive oxygen species (ROS) in patients with RA is higher than in healthy subjects. The aim of the present study was to investigate the level of the lipid peroxidation, antioxidant enzyme activities (CAT, SOD, GSH-Px), level of the –SH groups and GSH and Na⁺K⁺ ATPase activity in erythrocytes from patients with RA. There are no significant differences in CAT and GSH-Px activities. SOD activity is lower in RA patients than in the control group. Increase in the lipid peroxidation is observed in RA patients. Levels of the GHS and –SH groups are significantly lower in RA patients than in the control groups. Total ATPase and Na⁺K⁺ ATPase activities decrease in RA patients.     

老年高血压患者血管硬化与非酶糖基化及氧化应激的相关性研究

目的探讨老年高血压患者血管硬化与非酶糖基化标志物羧甲基赖氨酸(carboxymethylysineadducts,CML)以及氧化应激指标过氧化物歧化酶(superoxide dismutase,SOD)、血清丙二醛(malondialdehyde,MDA)的相关性。方法对85例老年高血压住院患者采用全自动动脉硬化测量仪测定脉搏波传导速度(PWV),并采用ELISA法检测其血清CML、SOD及MDA水平。结果单因素分析显示PWV与年龄、CML与MDA呈正相关(P0.05),CML与MDA呈正相关(P0.01),与SOD呈负相关(P0.01);多元回归分析结果显示PWV与年龄、CML及MDA呈正相关(P0.05)。结论老年高血压患者血管硬化程度与非酶糖基化水平、氧化应激均呈正相关,非酶糖基化水平与氧化应激亦呈正相关。     

Evidence that oxidative stress is increased in plasma from patients with maple syrup urine disease

Maple syrup urine disease (MSUD) or branched-chain α-keto aciduria (BCKA) is an inherited disorder caused by a deficiency of the branched-chain α-keto acid dehydrogenase complex (BCKAD) activity. The blockage of this pathway leads to tissue accumulation of the branched-chain amino acids (BCAA) leucine, isoleucine and valine and their respective keto-acids. The clinical features presented by MSUD patients include ketoacidosis, convulsions, coma, psychomotor delay and mental retardation. The mechanism of brain damage in this disease is still poorly understood. However, an increase in lipid peroxidation in vitro in cerebral cortex of young rats as well as a decrease in the antioxidant defenses has been previously observed. In the present work we evaluated different oxidative stress parameters, named reactive species of thiobarbituric acid (TBARS), total antioxidant reactivity (TAR) and total antioxidant status (TAS) in plasma of MSUD patients in order to evaluate whether oxidative stress is involved in this disorder. We verified a marked increase of plasma TBARS measurements, which is indicative of increased lipid peroxidation, as well as a decrease on plasma TAR reflecting a deficient capacity to efficiently modulate the damage associated with an increased production of reactive species. In contrast, TAS was not changed indicating that the total content of antioxidants in plasma of patients affected by MSUD was not altered. These results suggest that free radical generation is elicited in MSUD and is possibly involved in the pathophysiology of the tissue damage found in this disorder.