Enzyme Activity In Erythrocytes Research Articles

Evaluation of Superoxide Dismutase Enzyme Activity of Polymorphonuclear Leucocytes, Erythrocytes and Thrombocytes in Patients with Chronic Myeloproliferative Disorders

This study aimed to investigate the activity of the antioxidant enzyme superoxide dismutase (SOD) in the three main cell types in chronic myeloproliferative disorders (CMPD) patients, i.e. polymorphonuclear leucocytes (PMNLs), erythrocytes and thrombocytes, prior to therapy. Patients with reactive neutrophilia (RN) and healthy volunteers were included as controls. The SOD activity of PMNLs was significantly decreased in CMPD and RN patients compared with healthy volunteers, whereas the SOD activity of erythrocytes was found to be significantly increased in patients with CMPD and RN compared with healthy volunteers. There were no significant differences in the SOD activity of thrombocytes between CMPD patients, RN patients or healthy volunteers. This study indicates that the activity of the SOD enzyme in two cell types is different in CMPD patients compared with healthy subjects. Thus, SOD activity may be altered dependent on cell type and due to specific cell function.

Antioxidant Enzymes Show Adaptation to Oxidative Stress in Athletes and Increased Stress in Hemodialysis Patients

The aim of the study is to compare oxidative stress in hemodialysis patients in controls and in rowers. The patients are a model of decreased antioxidant capacity, and the athletes (rowers) are a model of the highest antioxidant capacity due to their chronic adaptation to demanding training. Thirty-five subjects participated in the study, 9 patients with end-stage renal disease treated by hemodialysis, 12 healthy young subjects from the normal population, and 14 rowers. The antioxidant enzymes catalase, superoxide dismutase, and glutathione peroxidase, as well as non-transferrin-bound iron as a promoter of free radical damage, were determined. Blood analysis was taken in dialysis patients in the morning, before the dialysis procedure. There was significantly higher activity of catalase in dialysis patients (catalase 4.26 +/- 0.35 mkat/g Hb) compared to the controls (catalase 2.73 +/- 0.38 mkat/g Hb) and rowers (catalase 1.71 +/- 0.30 mkat/g Hb). Superoxide dismutase activity was significantly lower (10.42 +/- 1.46 microkat/g Hb) than in the controls (11.94 +/- 1.18 microkat/g Hb) and rowers (14.09 +/- 0.92 microkat/g Hb). There was no significant differences between glutathione peroxidase activities in the three groups. Superoxide dismutase and Se were higher in rowers than in dialysis patients (P < 0.05). The concentrations of both non-transferrin-bound iron and ferritin were significantly higher in dialysis patients. Hemodialysis patients might have increased oxidative stress, which is characterized by significantly higher erythrocyte enzyme activity of catalase and lower activity of superoxide dismutase. Top rowers had increased superoxide dismutase and glutathione peroxidase, perhaps because of adaptation during training, which was not the case in dialysis patients and controls.

Effects of β‐carotene on antioxidant status in rats with chronic alcohol consumption

This study examined the effects of beta-carotene on antioxidant status in rats with chronic alcohol consumption. At the beginning of experiment (week 0), according to both the plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities, rats (n = 24) were divided into 3 groups and fed with a standard diet (group C), a diet containing ethanol (group E), or a diet containing ethanol and beta-carotene (group E+B). After 10 weeks, plasma AST and ALT, fat accumulation in the liver, antioxidant enzyme activities in erythrocytes and the liver, malondialdehyde (MDA), and alpha-tocopherol and retinol in plasma and hepatic samples were analyzed. The chronic alcohol diet significantly increased AST and ALT levels in plasma, and these changes were prevented by supplementing the diet with beta-carotene. Glutathione (GSH) in erythrocytes and in the liver was significantly elevated in rats fed with a diet containing beta-carotene. The results indicate that beta-carotene supplementation can prevent ethanol-induced liver damage and increase GSH concentrations in erythrocytes and the liver.

Capillary electrophoresis determination of thiopurine methyl transferase activity in erythrocytes

Thiopurine S-methyltransferase (TPMT) catalyzes methylation of thiopurine drugs (e.g. 6-mercaptopurine, azathioprine). Decreased activity of TPMT is associated with hematopoietic toxicity after administration of standard doses of the drugs. We developed capillary electrophoretic method for determination of TPMT enzyme activity in erythrocytes. Limit of quantification of the method is 1.5 μmol/L (S/N = 6). The recovery of 6-methylmercaptopurine was 87.5–94.8%, imprecision value (as CV, n = 10) was 1.68% (within-day) and 2.53% (between-day). Erythrocyte TPMT activities were measured in 60 healthy adult volunteers.

Blood glutathione status and activity of glutathione-metabolizing antioxidant enzymes in erythrocytes of young trotters in basic training

The aim of this study was to evaluate response of blood glutathione status and activity of glutathione-metabolizing antioxidant enzymes in erythrocytes of young trotters in basic training. Nine untrained trotters (aged 16-20 months) were exposed to a 4-month training program based on exercises at low-to-moderate intensity. The conditioning consisted of breaking the horses and running them on distances varying from 4 to 40 km a week. The workloads were increased on a 3-week basis. Exercise intensity was monitored by measuring heart rate and blood lactate. Blood samples were collected at rest, before (RES0) and after (RESt) the conditioning period; moreover, on the latter occasion (on day 112 of training), the blood was also taken immediately after the routine exercise (EXE0) and 60 min thereafter (EXE60). The whole blood samples were analysed for the concentration of reduced, oxidized and total glutathione (GSH, GSSG and TGSH, respectively), while the activities of glutathione peroxidase (GPX) and glutathione-disulfide reductase (GR) were determined in haemolysates. Additionally, the erythrocytic concentrations of oxidized nicotinamide adenine dinucleotide (NAD(+)) and its phosphate (NADP(+)) were measured. All investigated parameters except NAD(+) and reduced/oxidized glutathione ratio (GSH/GSSG) changed during the training period. Following the effortm GPX, NADP(+) and GSH/GSSG were significantly lower (p < 0.05, p < 0.01, p < 0.001, respectively) while GSSG was markedly higher than at rest (RESt). The drop in NADP(+), low GSH/GSSG and high GSSG concentration were sustained at EXE60. Glutathione-disulfide reductase activity was higher after the workout but only at EXE60 the increase in activity was significant. Despite the activities of the GSH-GSSG cycle, enzymes were considerably higher after the training period, the elevated concentration of GSSG and significantly lower GSH/GSSG ratio in the post-exercise measurements suggest that production of reactive oxygen species possibly exceeds the capacity of antioxidative defenses of immature trotters. A more balanced diet with additional antioxidant supplementation and a revision of the basic training protocol used herein are advised.

Effect of the β-amyloid peptide Aβ25–35 and fullerene C60 on the activity of enzymes in erythrocytes

The effect of the beta-amyloid peptide Abeta25-35 and fullerene C60 on the activity of the cytoplasmic enzymes lactate dehydrogenase (LDH) and glutathione peroxidase (GLP), and membrane-bound phosphofructokinase (PFK) and Na+,K(+)-ATPase in human erythrocytes has been studied. When used in combination, the cytotoxins decrease the activity of LDH and PFK in a nonadditive manner; in this case, Abeta25-35 protects PFK against the inhibitory effect of C60. The activity of LDH, GLP, and PFK decreases within the first 2-20 min of incubation of erythrocytes with Abeta25-35 in the absence of glucose. The addition of glucose sharply decreases the inhibitory action of Abeta25-35 on LDH and GLP but does not affect the fourfold decrease in activity of PFK; the activity of membrane-bound Na+,K(+)-ATPase does not depend on the presence of glucose. Possible mechanisms of interaction of Abeta25-35 and fullerene C60 with the erythrocyte membrane and enzymes are discussed.

Antioxidant effect of Ajuga iva aqueous extract in streptozotocin-induced diabetic rats

The purpose of this study was to investigate the possible antioxidant effect of an aqueous extract of Ajuga iva (Ai) in streptozotocin (STZ)-induced diabetic rats. Twelve diabetic rats were divided into two groups fed a casein diet supplemented or not with Ai (0.5%), for 4 weeks. In vitro, the Ai extract possessed a very high antioxidant effect (1 mg/ml was similar to those of trolox 300 mmol/l). The results indicated that plasma thiobarbituric acid reactive substances (TBARS) values were reduced by 41% in Ai-treated compared with untreated diabetic rats. TBARS concentrations were lower 1.5-fold in liver, 1.8-fold in heart, 1.9-fold in muscle and 2.1-fold in brain in Ai-treated than untreated group. In erythrocytes, Ai treatment increased significantly the activities of glutathione peroxidase (GSH-Px) (+25%) and glutathione reductase (GSSH-Red) (+22%). Superoxide dismutase activity was increased in muscle (+22%), while GSH-Px activity was significantly higher in liver (+28%), heart (+40%) and kidney (+45%) in Ai-treated compared with untreated group. Liver and muscle GSSH-Red activity was, respectively, 1.6- and 1.5-fold higher in Ai-treated than untreated diabetic group. Catalase activity was significantly increased in heart (+36%) and brain (+32%) in Ai-treated than untreated group. Ai treatment decreased plasma nitric oxide (-33%), carbonyls (-44%) and carotenoids (-68%) concentrations. In conclusion, this study indicates that Ajuga iva aqueous extract improves the antioxidant status by reducing lipid peroxidation and enhancing the antioxidant enzymes activities in plasma, erythrocytes and tissues of diabetic rats.

Activity of Antioxidative Enzymes in Erythrocytes after a Single Dose Administration of Doxorubicin in Rats Pretreated with Fullerenol C60(OH)24

In earlier in vitro investigations, fullerenol was shown to have a strong antioxidative capability. The present study examined the role of fullerenol as a potential antioxidative protector for doxorubicin-induced oxidative stress in the blood of rats through an investigation of the activity of glutathione-dependent enzymes (glutathione-S-transferase and glutathione peroxidase). It also assessed the influence of fullerenol on the number of blood cells (leukocytes and erythrocytes) as well as on the content of hemoglobin after a single dose administration of doxorubicin. Experiments were performed on six groups of adult male Wistar rats, each group containing eight individuals. Doxorubicin was administrated i.v. (tail vein) in a single dose of 10 mg/kg. Fullerenol C60(OH)24 was administrated to the treated animals i.p. (in doses 50, 100, 200 mg/kg) 30 min before the dosing with doxorubicin. The control group animals were given saline (1 ml/kg; i.p.). One group of animals was treated only with fullerenol (100 mg/kg i.p.). The animals were sacrificed 2 and 14 days after the treatment. Each experiment was repeated twice. The results may indicate that fullerenol induces a decrease in the antioxidative capacity of erythrocytes in oxidative stress conditions, whereas, without doxorubicin, the application of fullerenol did not induce any changes in the enzyme activity of erythrocytes. The results of GST activity might indicate that 50 mg/kg are not sufficient to protect from doxorubicin toxicity, while 200 mg/kg might be toxic for animals, judging from the increase in GST activity.

Catalase Activity, Serum Trace Element and Heavy Metal Concentrations, and Vitamin A, D and E Levels in Pre-Eclampsia

Catalase (antioxidant enzyme) activity in erythrocytes and serum levels of trace elements (copper, iron, zinc), heavy metals (cadmium, cobalt) and vitamins A (retinol), D (cholecalciferol) and E (alpha-tocopherol) were measured in 145 subjects comprising 47 pre-eclamptic pregnant women (PE), 48 healthy pregnant women (HP) and 50 healthy non-pregnant controls (NP). Catalase, vitamins A, D and E and levels of cobalt were significantly lower in the PE group compared with the HP and NP groups, whereas levels of copper, iron and cadmium were significantly higher in the PE group than in the HP and NP groups. Levels of zinc were significantly lower in both the PE and HP groups compared with the NP group. This assessment of oxidant/antioxidant imbalance in pregnant women could be useful in the early identification of pre-eclampsia and antioxidant supplementation in the early weeks of gestation might be useful.

OXIDATIVE EFFECTS AFTER PHOTODYNAMIC THERAPY IN RATS

The oxidative effects of photodynamic therapy (PDT) with 5-aminolevulinic acid (5-ALA) and chitosan (CS) were evaluated in Wistar rats s. c. inoculated with Walker 256 carcinoma. The animals were irradiated with red light (?=685 nm, D=50 J/cm2, 15 min) 3h after i.p administration of 250 mg/kg b.w. 5-ALA, 1.5-mg/kg b.w. CS or an associated treatment of 5-ALA and CS. The levels of lipid peroxides and protein carbonyls were determined in plasma and tumor tissues. The antioxidant capacity of plasma and tumor tissues as well as the antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) activities in erythrocytes and tumors were assessed. 24hs after the treatment, in 5-ALA treated animals the levels of lipid peroxides and protein carbonyls were significantly increased both in plasma and tumors. 5-ALA PDT decreased the erythrocyte antioxidant enzymes activities. An associated treatment with CS and 5-ALA produced the reduction of the lipid peroxides and protein carbonyls in plasma and the recovery of antioxidant enzymes activities. These results suggest the antioxidant properties of CS

Glucose‐6‐phosphate dehydrogenase deficiency protects against coronary heart disease

Previous studies suggest a reduction in cardiovascular risk among subjects expressing the glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49) deficient phenotype. We aimed to test this hypothesis in male subjects expressing the G6PD-deficient phenotype vs wild type G6PD. In a case-control study we examined consecutive patients admitted for acute myocardial infarction or unstable angina, and controls admitted for diagnoses other than coronary heart disease (CHD). The G6PD phenotype was determined by measuring the enzyme activity in erythrocytes, as the absorbance rate change due to NADPH reduction. The CHD risk associated with the G6PD phenotype was assessed with unconditional logistic regression. G6PD-deficient subjects were less frequently represented among cases (11.8%) than among controls (18.6%, p=0.002). The genetic condition of G6PD deficiency conveyed a significant reduction in CHD risk (OR=0.6; 95% CI 0.4 to 0.9). We confirm the hypothesis that subjects with the G6PD-deficient phenotype are less prone to CHD. We suggest that such a protective effect may be ascribable to a reduced 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA R) activity, a statin-like effect, as well as to a downregulation in NADPH oxidase activity with a consequent reduction in oxygen-free radical production.

Dietary chlorella supplementation improves oxidative stress induced by cadmium in SD rats

This study was designed to investigate the effect of chlorella supplementation on oxidative stress induced by dietary cadmium (Cd) in Sprague‐Dawley (SD) rats. Sixty male SD rats (14 week‐old) were fed diets containing 0%, 3% or 5% chlorella, and 0 ppm (−Cd) or 160 ppm (+Cd) Cd for 10 weeks. Serum and hepatic superoxide radical generation, erythrocyte and hepatic antioxidative enzyme activities (SOD, GPx, and catalase), and plasma MDA and renal 8‐hydroxy‐2′‐deoxyguanosine levels were measured. Serum superoxide radical generations of +Cd groups were significantly higher than −Cd groups, and 3% chlorella +Cd group was significantly lower than 0% chlorella +Cd group. Hepatic superoxide radical level in 5% chlorella −Cd group was significantly lower than 0% chlorella−Cd group. But, erythrocyte and hepatic SOD acitivities showed no difference among all the groups. Plasma MDA levels of 0% chlorella +Cd group were significantly higher than 0% chlorella −Cd group, and reduced in 3% chlorella +Cd group compared with 0% chlorella +Cd group. There findings suggest that chlorella supplementation showed antioxidative capacity against oxidative stress induced by dietary Cd. *This work was supported by the grants from Daesang.Co.Ltd. and the second stage of Brain Korea 21 project in 2007.

Direct Assay of Enzymes in Heme Biosynthesis for the Detection of Porphyrias by Tandem Mass Spectrometry. Uroporphyrinogen Decarboxylase and Coproporphyrinogen III Oxidase

We report new assays of enzymes uroporphyrinogen decarboxylase (UROD) and coproporphyrinogen III oxidase (CPO) in the heme biosynthetic pathway. The assays were developed for use in clinical diagnostics of inherited disorders porphyria cutanea tarda and hereditary coproporphyria, respectively. Electrospray ionization tandem mass spectrometry is used to monitor the decarboxylation of pentaporphyrinogen I or uroporphyrinogen III catalyzed by UROD and to determine the enzyme activity in human erythrocytes by measuring the production of coproporphyrinogen I or III. The Km value for pentaporphyrinogen I was measured as 0.17 +/- 0.03 microM. A mass spectrometric assay was also developed for the two-step decarboxylative oxidation of coproporphyrinogen III to protoporphyrinogen IX catalyzed by CPO in mitochondria from human lymphocytes (Km = 0.066 +/- 0.009 microM). The assays show good reproducibility, use simple workup by liquid-liquid extraction of enzymatic products, and employ commercially available substrates and internal standards.

Increased Oxidant Stress and Decreased Antioxidant Status in Erythrocytes of Rats Fed with Zinc-deficient Diet

The aim of this study was to evaluate the lipid peroxidation, nitric oxide (NO), and free radical scavenging enzyme activities in erythrocytes of zinc (Zn)-deficient rats and to investigate the relationship among these parameters in either group. Sixteen male rats with a weight of 40-50 g were used for the experiment. The rats were divided into control (n = 8) and Zn-deficient groups. At the end of the experiment, the animals were anesthetized with ketamine-HCl (Ketalar, 20 mg/kg(-1), i.p.), and the blood was collected by cardiac puncture after thoracotomy. Blood samples were collected in vacutainer tubes without and with K(3)-EDTA as anticoagulant. Erythrocyte catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GRD), glutathione-S-transferase (GST), superoxide dismutase (SOD) activities, total (enzymatic plus nonenzymatic) superoxide scavenger activity (TSSA), nonenzymatic superoxide scavenger activity (NSSA), antioxidant potential (AOP), and serum zinc (Zn) values in the Zn-deficient group were significantly lower than those of the control group, whereas NO and malondialdehyde (MDA) levels were significantly higher than those of the control group. The results show that Zn deficiency causes a decrease in antioxidant defense system and an increase in oxidative stress in erythrocyte of rats.

Lipid Peroxidation and Antioxidative Enzyme Activity in Erythrocytes of Workers Occupationally Exposed to Aluminium

Current research indicates that lipid peroxidation could have a role in aluminium toxicity. The aim of this study was to asses lipid peroxidation and antioxidative enzyme activity in erythrocytes of workers occupationally exposed to aluminium. We investigated a group of 59 workers (Al group) exposed to aluminium fumes (contamination factor F=8.07 to 13.47, national maximal allowed concentration value is 2 mg m-3). The control group (C group) consisted of 75 subjects employed in lime production who had not been occupationally exposed to aluminium or any known toxic substance. Erythrocyte aluminium concentrations were significantly higher in the exposed group than controls [Al group (8.41+/-3.66) microg L-1, C group (5.60+/-0.86) microg L-1, p<0.001]. In the Al group, erythrocyte malondialdehyde concentration was also significantly higher [Al group (189.59+/-81.27) micromol L-1, C group (105.21+/-49.62) micromol L-1, p<0.001] and antioxidative enzyme activity reduced for glucoso-6-phosphate-dehydrogenase [Al group (5.05+/-1.70) IU g-1 Hb, C group (12.53+/-4.12) IU g-1 Hb, p<0.001], glutathione reductase [Al group (1.41+/-0.56) IU g-1 Hb, C group (1.89+/-0.57) IU g-1 Hb, p<0.001], glutathione peroxidase [Al group (12.37+/-5.76) IU g-1 Hb, C group (15.54+/-4.85) IU g-1 Hb, p<0.001], catalase [Al group (116.76+/-26.60) IU g-1 Hb, C group (158.81+/-71.85) IU g-1 Hb, p<0.001] and superoxide dismutase [Al group (1175.8+/-149.9) IU mg-1 Hb, C group (1377.9+/-207.5) IU mg-1 Hb, p<0.001].

Effects of Electromagnetic Radiation Use on Oxidant/Antioxidant Status and DNA Turn-over Enzyme Activities in Erythrocytes and Heart, Kidney, Liver, and Ovary Tissues From Rats: Possible Protective Role of Vitamin C

ABSTRACTIn this study, the aim was to investigate possible effects of Electromagnetic Radiation (EMR) use on oxidant and antioxidant status in erythrocytes and kidney, heart, liver, and ovary tissues from rats, and possible protective role of vitamin C. For this aim, 40 Wistar albino female rats were used throughout the study. The treatment group was exposed to EMR in a frequency of 900 MHz, the EMR plus vitamin C group was exposed to the same EMR frequency and given vitamin C (250 mg/kg/day) orally for 4 weeks. There were 10 animals in each group including control and vitamin C groups. At the end of the study period, blood samples were obtained from the animals to get erythrocyte sediments. Then the animals were sacrificed and heart, kidney, liver, and ovary tissues were removed. Malondialdehyde (MDA) levels and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), xanthine oxidase (XO), and adenosine deaminase (ADA) enzyme activities were measured in the tissues and erythrocytes. It was observed that MDA level, XO, and GSH-Px activities significantly increased in the EMR group as compared with those of the control group in the erythrocytes. In the kidney tissues, it was found that MDA level and CAT activity significantly increased, whereas XO and ADA activities decreased in the cellular phone group as compared with those of the control group. However, in the heart tissues it was observed that MDA level, ADA, and XO activities significantly decreased in the cellular phone group as compared with those of the control group. The results suggest that EMR at the frequency generated by a cell phone causes oxidative stress and peroxidation in the erythrocytes and kidney tissues from rats. In the erythrocytes, vitamin C seems to make partial protection against the oxidant stress.

Carbamazepine-Induced Hemolytic and Aplastic Crises Associated with Reduced Glutathione Peroxidase Activity of Erythrocytes

Although pure red cell aplasia is a well-known side effect of carbamazepine treatment, intravascular hemolytic anemia is rare. We describe a 5-year-old boy who developed concurrent intravascular hemolytic anemia and erythroblastopenia, probably due to carbamazepine. Carbamazepine treatment was subsequently discontinued, and the patient was treated with red blood cell transfusions, haptoglobin, and methylprednisolone. His hematologic abnormalities were almost fully recovered within 2 weeks. Examination of the patient's and mother's erythrocyte enzyme activities revealed mildly decreased erythrocyte glutathione peroxidase (GSH-Px) activity. We speculate that patients with reduced GSH-Px activity are at a high risk of developing carbamazepine-induced hemolytic crisis and/or aplastic crisis.

Associations Between GPX1 Pro198Leu Polymorphism and Erythrocyte GPX Activity and Risk of Colorectal Cancer

ISEE-476 Objective: GPX1 encodes the enzyme glutathione peroxidase 1 (GPX1), which may counteract oxidative DNA damage caused by reactive oxygen species from environmental and lifestyle sources. We examined prospectively whether the GPX1 Pro198Leu polymorphism or low enzyme activity in erythrocytes increases the risk of colorectal cancer, and assessed the interactions between the polymorphism/enzyme activity and dietary components or smoking in risk of colorectal cancer. Material and Methods: We identified 375 cases and selected a comparison group of 779 individuals matched on gender, all nested in the prospective “Diet, Cancer and Health” study of 57,053 Danes. Genotype was determined by endpoint reading on a Sequence Detection system ABI 7500. GPX enzyme activity was measured on a Roche/Hitachi 912 analyzer. Information on dietary components and smoking was obtained from questionnaires filled in at enrolment in 1993 to 1997. Results: We found no association between the GPX1 polymorphism and colorectal cancer, but observed statistically significant interaction (P = 0.01) between the polymorphism and alcohol consumption with an incidence rate ratio (IRR) of colorectal cancer of 1.47 (95% CI: 1.17–1.84) per 10 g alcohol intake per day among homozygous 198Leu carriers. Among these subjects IRR was 1.67 (CI: 1.06–2.65) per 10 g tobacco per day (P = 0.06). We found correlation between the GPX1 polymorphism and enzyme activity (P = 0.05). GPX activity was not associated with colorectal cancer. The activity was negatively correlated with smoking intensity (r = −0.12, P < 0.0001) and positively correlated with intake of fruits and vegetables (r = 0.09, P = 0.0012). No association was observed between GPX activity and alcohol consumption. Conclusions: Interaction was observed between alcohol consumption and the GPX1 Pro198Leu polymorphism in relation to colorectal cancer, which suggests that an adverse association between alcohol and colorectal cancer may be strongest among homozygous 198Leu carriers. GPX activity correlated with the polymorphism. Smoking intensity and intake of fruit and vegetables were predictors for GPX activity.

Oxidative stress in patients with COPD and pulmonary hypertension

Oxidative stress plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Oxidant/antioxidant imbalance has also been reported in various forms of pulmonary hypertension. The present study aimed to assess systemic oxidative stress, as reflected by serum malondialdehyde (MDA) concentrations and activities of antioxidant enzymes in erythrocytes [glutathione peroxidase (GPX), superoxide dismutase (SOD) and catalase (CAT)] in patients with and without pulmonary hypertension secondary to COPD. Seventy-five patients (58 male) with COPD (mean age 65.1 +/- 1.2 years; mean smoking history 35.6 +/- 3.8 pack-years) were studied. Twenty-one healthy non-smokers served as a control group. Pulmonary function was evaluated with body plethysmography; mean and systolic pulmonary artery pressures (Ppa) were assessed with Doppler echocardiography. Serum concentrations of MDA and activities of GPX, SOD and CAT in washed red blood cells were measured using spectrophotometry. Pulmonary hypertension was present in 28 patients with COPD (systolic Ppa: 46.4 +/- 2.3 mmHg; mean Ppa: 26.0 +/- 1.9 mmHg) and absent in 47 (systolic Ppa: 22.9 +/- 0.8 mmHg; mean Ppa: 13.4 +/- 0.6 mmHg). Compared with the healthy control group, all the patients (with or without pulmonary hypertension) had higher serum MDA concentrations (1.5 +/- 0.1 versus 2.3 +/- 0.1 versus 2.3 +/- 0.1 nmol/mL, ANOVA, P < 0.001) and lower erythrocyte GPX activity (51.3 +/- 3.2 versus 42.2 +/- 2.0 versus 41.3 +/- 2.5 U/g Hb, P = 0.029), whereas SOD (1121.1 +/- 29.0 versus 1032.6 +/- 21.8 versus 1032.7 +/- 36.2 U/g Hb, P = 0.063) and CAT activities (4.9 +/- 0.2 versus 4.6 +/- 0.1 versus 4.7 +/- 0.2 U/g Hb; P= 0.454) were similar. No differences were observed in serum MDA concentrations or activities of GPX, SOD and CAT in erythrocytes between COPD patients with and without pulmonary hypertension. The study demonstrates the presence of oxidative/antioxidative imbalance in the systemic circulation in patients with COPD: compared with healthy subjects, COPD patients had higher serum MDA concentrations and lower GPX activity in erythrocytes. The magnitudes of the increase in MDA and reduction in GPX activity were similar in COPD patients with pulmonary hypertension and in those with normal pulmonary artery pressures.

Erythrocyte susceptibility to oxidative stress and antioxidant status in patients with type 1 diabetes

In this study, malondialdehyde (MDA) level as an index of erythrocyte susceptibility to oxidative stress and antioxidant defense system (glutathione level (GSH), glutathione peroxidase enzyme activity (GPx) in erythrocytes and ferric reducing ability of plasma (FRAP) as the total plasma antioxidant capacity were measured in 35 patients with type 1 diabetes and 28 age and sex-matched normal subjects. MDA level was significantly elevated in diabetic patients (650.9 ± 144.3 nmol/g versus 476.5 ± 138.5 nmol/g Hb, P < 0.001). The level of MDA was positively correlated with duration of diabetes ( r = 0.29, P < 0.05) and HbA 1C ( r = 0.39, P < 0.05) and negatively with FRAP ( r = −0.3, P < 0.05). The level of GSH and FRAP were lower in patients than controls (7.05 ± 1.6 μmol/g versus 8.24 ± 0.9 μmol/g Hb, and 389.05 ± 82.3 μmol/l versus 520.4 ± 124.1 μmol/l, respectively, P < 0.001). GPx activity was not significantly different between the two groups. GSH and FRAP were negatively correlated with HbA 1C ( r = −0.334, P < 0.01 and r = −0.5, P < 0.01, respectively). In conclusion, there seems to be an increased susceptibility to oxidative stress and decreased antioxidant defense in patients with type 1 diabetes, which may be due to poor glycemic control.