Enzyme Activity In Erythrocytes Research Articles

Could cholesterol bound to haemoglobin be a missing link for the occasional inverse relationship between superoxide dismutase and glutathione peroxidase activities?

The concept of an anti-oxidant defence system as a means to prevent oxidative cell damage implies balanced activities of anti-oxidant defence enzymes. As well as positive correlations between anti-oxidant enzyme activities in human erythrocytes, it has been observed that sometimes when glutathione peroxidase activity is increased, CuZn-superoxide dismutase activity is decreased. In our current study we have examined the plasma lipid profile and the anti-oxidant defence enzymes in erythrocytes from humans, pigs, and bulls. We found that a negative correlation existed between CuZn-superoxide dismutase and glutathione peroxidase activities in human erythrocytes when the concentrations of both plasma triglycerides and total cholesterol were high. This correlation was also found in pig erythrocytes, but not in bull erythrocytes. We propose that cholesterol could affect membrane lipid peroxidation and superoxide generation in erythrocytes via the recently found fraction of cholesterol bound to haemoglobin, termed haemoglobin-cholesterol.

Role of antioxidant systems, lipid peroxidation, and nitric oxide in postmenopausal osteoporosis

In this study we assessed activities of antioxidant enzymes, lipid peroxidation end-products, and nitric oxide (NO) levels in women with postmenopausal osteoporosis (PMO). Relationship between oxidative stress parameters and NO levels with bone mineral density (BMD) and clinical variables influencing bone mass and health related quality of life measures was also investigated in women with PMO. Postmenopausal women (n=87), aged 40-65, without previous diagnosis or treatment for osteoporosis and independent in daily living activities were included. BMD was measured at the lumbar spine and proximal femur using dual-X-ray absorptiometry (DXA). Erythrocyte catalase (CATe) enzyme activity, erythrocyte and plasma enzyme activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and lipid peroxidation end-product malondialdehyde (MDA) and nitrite/nitrate levels, by product of NO were studied. A total of 23 healthy non-porotic women were included as controls. Women with PMO had significantly lower erythrocyte CATe enzyme activity and higher erythrocyte malondialdehyde (MDAe) and erythrocyte nitric oxide (NOe) levels in comparison to controls whereas erythrocyte SODe and GSH-Px enzyme activity was similar. In plasma, osteoporotic women had significantly higher SOD enzyme activity and higher MDA levels whereas similar GSH-Px enzyme activity and NO levels compared to non-porotic controls. Significant correlation was found between erythrocyte SODe, CATe enzyme activity and NOe levels with proximal femur BMD. Some of the quality of life scores as pain, mental, and social functions correlated with antioxidant enzyme activities and NO levels.Consequently, oxidative stress markers may be an important indicator for bone loss in postmenopausal women. Further researches assessing the oxidative stress markers and NO in bone tissue and changes with anti-osteoporotic drugs would be valuable to better understand the role of free radicals, antioxidants, and NO in the regulation of bone mass.

Evaluation of the Influence of Antiepileptic Therapy on Antioxidant Enzyme Activity and Lipid Peroxidation in Erythrocytes of Children With Epilepsy

The aim of this study was to evaluate the influence of antiepileptic therapy on antioxidant enzyme activity and lipid peroxidation in the erythrocytes of children with epilepsy. For this purpose, the activity of superoxide dismutase, glutathione peroxidase, and glutathione reductase and the malondialdehyde concentration in 61 healthy children and 90 children with epilepsy were measured. The activities of all of these enzymes were insignificantly higher, whereas the malondialdehyde concentration was significantly lower in the patients treated with carbamazepine monotherapy. In patients treated with valproate monotherapy, the activities of all enzymes were insignificantly lower, whereas the malondialdehyde concentration was insignificantly higher. In patients treated with polytherapy, the activity of superoxide dismutase was insignificantly lower, whereas the activity of glutathione peroxidase and glutathione reductase was insignificantly higher and the malondialdehyde concentration was lower. There were differences in glutathione reductase activity between the valproate monotherapy group and both the carbamazepine monotherapy and polytherapy groups and in malondialdehyde concentrations between the carbamazepine and valproate groups. The results indicate that the oxidant-antioxidant balance in children with epilepsy is modified by antiepileptic therapy.

Evaluation of the Influence of Antiepileptic Therapy on Antioxidant Enzyme Activity and Lipid Peroxidation in Erythrocytes of Children With Epilepsy

The aim of this study was to evaluate the influence of antiepileptic therapy on antioxidant enzyme activity and lipid peroxidation in the erythrocytes of children with epilepsy. For this purpose, the activity of superoxide dismutase, glutathione peroxidase, and glutathione reductase and the malondialdehyde concentration in 61 healthy children and 90 children with epilepsy were measured. The activities of all of these enzymes were insignificantly higher, whereas the malondialdehyde concentration was significantly lower in the patients treated with carbamazepine monotherapy. In patients treated with valproate monotherapy, the activities of all enzymes were insignificantly lower, whereas the malondialdehyde concentration was insignificantly higher. In patients treated with polytherapy, the activity of superoxide dismutase was insignificantly lower, whereas the activity of glutathione peroxidase and glutathione reductase was insignificantly higher and the malondialdehyde concentration was lower. There were differences in glutathione reductase activity between the valproate monotherapy group and both the carbamazepine monotherapy and polytherapy groups and in malondialdehyde concentrations between the carbamazepine and valproate groups. The results indicate that the oxidant-antioxidant balance in children with epilepsy is modified by antiepileptic therapy. (J Child Neurol 2006;21:558–562; DOI 10.2310/7010.2006.00115).

RETRACTED: Validation and application of a high-performance liquid chromatographic-based assay for determination of the inosine 5′-monophosphate dehydrogenase activity in erythrocytes

Thiopurine drug monitoring has become an important issue in treating children with acute lymphoblastic leukaemia (ALL). In this population, a genetic polymorphism causes wide differences in the activity of thiopurine S-methyletransferase (TPMT)--the rate-limiting enzyme of the thiopurine degradation metabolism--leading to the necessity of drug dose adjustments. It is not yet known if similar differences exist in the inosine 5'-monophosphate dehydrogenase (IMPDH; EC 1.1.1.205), the rate-limiting enzyme of the thiopurine synthesis. To test this, we established and validated a high-performance liquid chromatographic (HPLC)-based assay to determine the IMPDH enzyme activity in erythrocytes. The remarkable features of this assay are its simple erythrocyte separation/haemolysis and assay conditions and a distinct segregation of xanthosine 5'-monophosphate (XMP) from the clear supernatant after precipitation. The probes were processed without a time-consuming extraction and heating procedure and the assay demonstrated a good intra- and interday stability as well as a recovery rate of approximately 100%. The IMPDH enzyme activity was measured in erythrocytes of 75 children with diagnosis of ALL before starting antileukaemic therapy and their activity compared to those of 35 healthy adult controls. The measured enzyme activity was wide ranging in both groups. The individual enzyme activity differences observed in children with ALL might led to differences in the thionucleotide levels in those undergoing the standard thiopurine dose regimen.

An evaluation of cytosolic erythrocyte carbonic anhydrase and catalase in carcinoma patients: An elevation of carbonic anhydrase activity

Objectives: The antioxidant enzyme catalase and the CO 2/HCO 3 − exchange enzyme carbonic anhydrase are both present in significant amounts in the cytosol of erythrocytes. The aim of the present study was to investigate whether these erythrocyte enzyme activities are altered in patients who have carcinoma. Design and methods: Cytosolic erythrocyte enzyme activities were measured in 108 cancer patients presenting with carcinoma at one of variable sites, prior to clinical treatment. These were compared with an age- and sex-matched control group of 31 healthy volunteers. Results: Mean (±SD) catalase activities did not differ significantly, i.e. 0.0035 (±0.0015) EU/ml in carcinoma patients vs. 0.0031 (±0.00075) EU/ml in controls. However, mean carbonic anhydrase activities of 204 (±91) EU/ml in the carcinoma patients were significantly higher than the 158 (±35) EU/ml in controls ( P value of 0.0065). Conclusion: Cytosolic erythrocyte carbonic anhydrase levels may warrant further investigation as a potential peripheral marker in cancer.

Effect of melatonin on enzyme activities of glutathione reductase from human erythrocytes in vitro and from rat erythrocytes in vivo

The in vivo and in vitro effects of melatonin on enzyme activity of glutathione reductase (Glutathione: NADP(+) oxidoreductase, EC 1.8.1.7; GR) were investigated in this study. Glutathione reductase was purified from human erythrocytes 5.823-fold with a yield of 24% by ammonium sulfate fractionation, affinity chromatography on 2',5'-ADP Sepharose 4B and gel filtration chromatography on Sephadex G-200. Enzyme activity was determined by the Calberg and Mannervik method using a spectrophotometer at 340 nm. For in vitro experiments, the enzyme activity increased at 0.02 mM and decreased at 0.08 mM melatonin concentration and reached a plateau above 0.08 mM. Melatonin was administered 10 mg/kg intraperitoneally (ip) and had a stimulatory effect on the enzyme. In vivo studies were performed for melatonin in Sprague-Dawley rats and time-dependent effects were demonstrated. Glutathione reductase activity in erythrocytes was increased more by melatonin at 1 and 3 h. These results indicate that pharmacological levels of melatonin increased enzyme activity in erythrocytes. They also indicate that melatonin may be pharmacologically useful in patients with a deficiency of the enzyme in red blood cells causing hemolytic anemia.

Free radicals, lipid peroxidation and the antioxidant system in the blood of cows and newborn calves around calving

The oxidative stress of birth in cattle ( Bos taurus) was evaluated by measuring steady state concentration of free radicals in whole blood, rate of lipid peroxidation and activity of antioxidant enzymes in erythrocytes, antioxidant capacity of blood plasma in 14 calves at birth and four times after birth until 3 weeks of age and also in their mothers at calving. The same parameters were also measured in 58 dairy cows before calving, at parturition and after calving. Free radical concentration in the blood of newborn calves was higher than in cows confirming that birth means oxidative stress for calves. Red blood cell malondialdehyde in calves was the highest at birth and following the first solid feed intake at the third week. Superoxide dismutase activity increased in calves during the first three weeks of life. Ferric reducing ability of plasma was higher in calves at birth than in cows and decreased thereafter. Higher superoxide dismutase activity in red blood cells and lower ferric reducing ability of plasma in dairy cows was found at calving compared to the average of all pre- and post-calving results. We conclude that the blood of newborn calves is well prepared to deal with the oxidative stress of birth, and that such a stress is present even when some fingerprint markers of redox imbalance show no apparent alterations. Stress of calving has minor effects on the antioxidant system of cows.

Biological effects of fruit and vegetables

A strong and persistent effect of plant-derived foods on the prevention of lifestyle diseases has emerged from observational studies. Several groups of constituents in plants have been identified as potentially health promoting in animal studies, including cholesterol-lowering factors, antioxidants, enzyme inducers, apoptosis inducers etc. In human intervention studies the dose levels achieved tend to be lower than the levels found to be effective in animals and sampling from target organs is often not possible. A controlled dietary human intervention study was performed with forty-three volunteers, providing 600 g fruit and vegetables/d or in the controls a carbohydrate-rich drink to balance energy intake. Surrogate markers of oxidative damage to DNA, protein and lipids, enzymic defence and lipid metabolism were determined in blood and urine. It was found that a high intake of fruit and vegetables tends to increase the stability of lipids towards oxidative damage. Markers of oxidative enzymes indicate a steady increase in glutathione peroxidase (GPX1) activity in erythrocytes during intervention with fruit and vegetables but there is no effect on GPX1 transcription levels in leucocytes. No change occurs in glutathione-conjugating or -reducing enzyme activities in erythrocytes or plasma, and there are no effects on the transcription of genes involved in phase 2 enzyme induction or DNA repair in leucocytes. Fruit and vegetable intake decreases the level of total cholesterol and LDL-cholesterol, but does not affect sex hormones. In conclusion, it has been shown that total cholesterol and LDL-cholesterol, markers of peripheral lipid oxidation, and erythrocyte GPX1 activity are affected by high intakes of fruit and vegetables. This finding provides support for a protective role of dietary fruit and vegetables against CVD.

N-3 Fatty acids modulate antioxidant status in diabetic rats and their macrosomic offspring

We investigated the role of dietary n-3 polyunsaturated fatty acids (n-3 PUFA) in the modulation of total antioxidant status in streptozotocin (STZ)-induced diabetic rats and their macrosomic offspring. Female wistar rats, fed on control diet or n-3 PUFA diet, were rendered diabetic by administration of five mild doses of STZ on day 5 and were killed on days 12 and 21 of gestation. The macrosomic (MAC) pups were killed at the age of 60 and 90 days. Lipid peroxidation was measured as the concentrations of plasma thiobarbituric acid reactive substances (TBARS), and the total antioxidant status was determined by measuring (i) plasma oxygen radical absorbance capacity (ORAC), (ii) plasma vitamin A, E and C concentrations, and (iii) antioxidant enzymes activities in erythrocytes. The plasma lipid concentrations and fatty acid composition were also determined. Diabetes increased plasma triglyceride and cholesterol concentrations, whereas macrosomia was associated with enhanced plasma cholesterol and triglyceride levels, which diminished by feeding n-3 PUFA diet. N-3 PUFA diet also reduced increased plasma TBARS and corrected the decreased ORAC values in diabetic rats and their macrosomic offspring. EPAX diet increased the diminished vitamin A levels in diabetic mothers and vitamin C concentrations in macrosomic pups. Also, this diet improved the decreased erythrocyte superoxide dismutase and glutathione peroxidase activities in diabetic and macrosomic animals. Diabetes and macrosomia were associated with altered lipid metabolism, antioxidant enzyme activities and vitamin concentrations. N-3 PUFA diet improved hyperlipidemia and restored antioxidant status in diabetic dams and MAC offspring.

P.1.c.045 The effects of risperidone, olanzapine and haloperidol on enzyme activities in erythrocytes and plasma of rats

The subthalamic nucleus (STN) receives direct dopaminergic innervation from the substantia nigra pars compacta that degenerates in Parkinson's disease. The present study aimed to investigate the role of dopaminergic denervation of STN in the origin of levodopa-induced dyskinesias. Rats were distributed in four groups which were concomitantly lesioned with 6-OHDA or vehicle (sham) in the STN and in the medial forebrain bundle (MFB) as follows: a) MFB-sham plus STN-sham, b) MFB-sham plus STN-lesion, c) MFB-lesion plus STN-sham, and d) MFB-lesion plus STN-lesion. Four weeks after lesions, animals were treated with levodopa (6 mg/kg with 15 mg/kg benserazide i.p.) twice daily for 22 consecutive days. Abnormal involuntary movements were measured. In situ hybridization was performed measuring the expression of striatal preproenkephalin, preprodynorphin, STN cytochrome oxidase (CO) and nigral GAD67 mRNAs. STN 6-OHDA denervation did not induce dyskinesias in levodopa-treated MFB-sham animals but attenuated axial (p < 0.05), limb (p < 0.05) and orolingual (p < 0.01) dyskinesias in rats with a concomitant lesion of the nigrostriatal pathway. The attenuation of dyskinesias was associated with a decrease in the ipsilateral STN CO mRNA levels (p < 0.05). No significant differences between MFB-lesion plus STN-sham and MFB-lesion plus STN-lesion groups in the extent of STN dopaminergic denervation were observed. Moreover, intrasubthalamic microinfusion of dopamine in the MFB-lesion plus STN-lesion group triggered orolingual (p < 0.01), but not axial or limb, dyskinesias. These results suggest that dopaminergic STN innervation influences the expression of levodopa-induced dyskinesias but also the existence of non dopaminergic-mediated mechanisms. STN noradrenergic depletion induced by 6-OHDA in the STN needs to be taken in account as a possible mechanism explaining the attenuation of dyskinesias in the combined lesion group.

The effects of extracorporeal shock wave lithotripsy on antioxidant enzymes in erythrocytes

The effects of extracorporeal shock wave lithotripsy (ESWL) on patients undergoing ESWL for renal stone treatment have been studied using activities of glucose-6-phosphate dehydrogenase (G6PDH), superoxide dismutase (SOD) and catalase (CAT), and levels of malondialdehyde (MDA) in the erythrocyte haemolysate. The study included 23 patients (eight women, 15 men with an age range of 23-57 years). Blood samples were taken 5 min before ESWL, in addition to 1 h and 5 days after termination of treatment. Enzyme activities and MDA levels in erythrocytes were measured spectrophotometrically. When compared with the values obtained before ESWL, erythrocyte G6PDH (p = 0.015), SOD (p = 0.036) and CAT (p = 0.01) activities were found to be significantly reduced at the first hour after ESWL. On the fifth day after ESWL, erythrocyte enzyme activities were normalized to the values obtained before ESWL. Although there was a significant difference between values before and 1 h after ESWL (p = 0.003), no difference was detected between 1 h after ESWL and 5 days after ESWL (p > 0.05) in terms of MDA values. The findings of the present study revealed that erythrocyte lipid peroxidation might be induced and antioxidative defence mechanism may be transiently impaired by ESWL.

Contribution of insulin resistance to reduced antioxidant enzymes and vitamins in nonobese Korean children

Background The prevalence of insulin resistance has been reported in nonobese, nondiabetic healthy individuals. We examined the relationship between insulin resistance and the reduced antioxidant systems of plasma lipid soluble vitamins and antioxidant enzymes in erythrocytes and to determine the contributing factors to the antioxidant systems in nonobese children. Methods We measured blood lipid profiles, glucose, insulin concentrations, plasma antioxidant vitamins and erythrocytic antioxidant enzyme activities of 103 Korean children in the absence of obesity. Insulin resistance was estimated by homeostasis model assessment of insulin resistance (HOMA-IR). Results A significant inverse relationships between HOMA-IR and lipid corrected β-carotene ( r = − 0.233, p < 0.05), α-tocopherol ( r = − 0.370, p < 0.0001) were observed. In addition, increased HOMA-IR was significantly related to the decreased activities of superoxide dismutase ( r = − 0.226, p < 0.05) and catalase ( r = − 0.261, p < 0.05). Stepwise multiple linear regression analyses showed that HOMA-IR was the independent factor to determine the antioxidant status such as plasma α-tocopherol ( β = − 0.379, p < 0.0001), β-carotene ( β = − 0.243, p < 0.05), SOD ( β = − 0.230, p < 0.05), and catalase activity ( β = − 0.255, p < 0.05) after adjusting percent ideal body weight, waist circumference, gender, blood lipids and leptin levels in nonobese children. Conclusion The reduced antioxidant status in insulin resistance state even in nonobese children suggests the importance of early nutritional intervention with features of insulin resistance.

Effect of pentylenetetrazol-induced epileptic seizure on the antioxidant enzyme activities, glutathione and lipid peroxidation levels in rat erythrocytes and liver tissues

Objectives: In order to clarify whether oxidative stress accompanies epilepsy, we examined the effects of pentylenetetrazol (PTZ)-induced epilepsy on the lipid peroxidation and antioxidant enzyme activities in erythrocytes and liver tissues of adult Wistar rats. Materials and methods: The activities of antioxidative enzymes (glucose-6-phosphate dehydrogenase (G-6-PD)), copper, zinc-superoxide dismutase (Cu,Zn-SOD), catalase (CAT), selenium-dependent glutathione peroxidase (Se-GSH-Px) and the levels of reduced glutathione (GSH) and thiobarbituric acid-reactive substances (TBARS) were measured in erythrocytes and liver tissues of pentylenetetrazol (PTZ)-induced epileptic adult Wistar rats. Results: Single PTZ treatment in a convulsive dose of 50 mg/kg significantly reduced the erythrocyte Cu,Zn-SOD, CAT enzyme activities and GSH levels compared to controls ( P < 0.001, P < 0.001, P < 0.05, respectively). Erythrocyte and liver tissue TBARS levels in the epileptic group were significantly higher than controls ( P < 0.0001). There was a significant decrease in liver tissue Cu,Zn-SOD activity and GSH levels in the epileptic group ( P < 0.0001), whereas significantly higher activities of G-6-PD and Se-GSH-Px were found in the epileptic group. Conclusions: Our results demonstrate a generalized diminished antioxidant activity and increased TBARS level indicating enhanced oxidative stress in the liver and erythrocytes of epileptic rats. Increased oxidative stress in the liver of epileptic rats might be due to the activation of the recently found glutamate receptors in the liver. These findings suggest that the use of antioxidants with antiepileptic drugs and new drugs such as type-5 metabotropic glutamate receptor (mGlu5) antagonist (MPEP) might protect erythrocytes and liver tissue against anoxic damage and oxidative stress.

Study of Tobacco Habits and Alterations in Enzymatic Antioxidant System in Oral Cancer

Aim and Objective: Tobacco is a major etiological factor for oral cancer development, accounting 30–40% of all cancer cases in India. Tobacco consumption generates free radicals and causes oxidative damages. In order to counteract these lethal effects, normal living cells have multiple antioxidant defense systems in a cascade manner. Thus, it seems that studying biological parameters, like antioxidant enzyme system, may be helpful in risk assessment and early diagnosis of oral cancer. Therefore, we analyzed erythrocytic and tissue antioxidant enzyme activities in terms of glutathione-S-transferase (GST), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and plasma thiol levels. Materials and Methods: Study included healthy controls with no habit of tobacco (NHT, n = 25), controls with habit of tobacco (WHT, n = 31) and oral cancer patients (n = 52). All the parameters were analyzed with highly sensitive and specific spectrophotometric methods. Results: Erythrocytic SOD and plasma thiol levels were significantly lower (p = 0.03), while GPx and CAT levels were higher (p = 0.017) in WHT as compared to NHT. No significant changes in GST and GR levels were observed between NHT and WHT. GST, GR, SOD and CAT activities were significantly higher (p = 0.05, p < 0.001, p = 0.003 and p < 0.001, respectively) while GPx and thiol levels were lower (p = 0.035 and p < 0.001, respectively) in oral cancer as compared to WHT. Odds ratio for erythrocytic GR, SOD, CAT and plasma thiol showed significantly higher risk of oral cancer development in WHT. Mean levels of SOD and CAT were increased, while GPx and thiol were decreased with the increase in habit duration in oral cancer. GST, GR and SOD activities were significantly higher (p = 0.0001, p = 0.005 and p = 0.005, respectively), while, CAT and thiol levels were lower (p = 0.0001 and p = 0.015, respectively) in malignant tissues as compared to adjacent normal tissues. Conclusion: The data revealed that evaluation of antioxidant enzyme activities and thiol levels in WHT can be helpful to identify individuals at a higher risk of oral cancer development

High Prevalence of Glucose-6-Phosphate Dehydrogenase Deficiency without Gene Mutation Suggests a Novel Genetic Mechanism Predisposing to Ketosis-Prone Diabetes

Ketosis-prone diabetes (KPD) is mostly observed in males of West African descent and is characterized by phasic or permanent insulin dependence without apparent autoimmune process. KPD subjects display a propensity to hyperglycemia-induced acute insulin deficiency, suggesting that they exhibit a propensity to oxidative stress in beta-cells. The enzyme glucose-6-phosphate dehydrogenase (G6PD) is a defense mechanism against oxidative stress, and G6PD deficiency, an X-linked genetic disorder with male predominance, is frequent in West Africans. We hypothesized that mutations in the G6PD gene could predispose to KPD. We studied G6PD erythrocyte enzyme activity and the insulin secretory reserve (glucagon-stimulated C peptide) in a cohort of hospitalized West Africans with KPD (n = 59) or type 2 diabetes (T2DM; n = 59) and in normoglycemic controls (n = 55). We also studied the G6PD gene in an extended population of KPD patients (n = 100), T2DM patients (n = 59), and controls (n = 85). The prevalence of G6PD deficiency was higher in KPD than in T2DM and controls (42.3%; 16.9%; 16.4%; P = 0.01). In KPD, but not in T2DM, insulin deficiency was proportional to the decreased G6PD activity (r = 0.33; P = 0.04). We found no increase in the prevalence of G6PD gene mutations in KPD compared with T2DM and controls. Rather, we found a 20.3% prevalence of G6PD deficiency in KPD without gene mutation. This study suggests that 1) G6PD deficiency alone is not causative of KPD; and 2) alterations in genes controlling both insulin secretion and G6PD-mediated antioxidant defenses may contribute to the predisposition to KPD in West Africans.

Influence of Epoietinum Therapy on the Oxidative Stress in Haemodialysis Patients

Background: The causes of oxidative stress in haemodialysis (HD) patients are still controversial. Beside the uraemic state and dialysis-related factors, adjuvant drug therapies such as epoietinum (rHuEpo) and intravenous iron were involved. Methods: Several parameters related to oxidative stress were assessed by spectrophotometry in stable HD patients, treated for at least 2 months with epoietinum (n = 14; mean dose = 97.7 ± 19.1 U/kg/week) or not (n = 15), none of them on iron therapy, and in 13 controls. Plasma thiobarbituric acid-reactive substances (TBARS) were used as markers of reactive species generation. Erythrocyte and plasma antioxidant systems, reflected by non-protein erythrocyte thiols, and erythrocyte enzyme activities – superoxide dismutase (SOD), glutathione peroxidase, catalase and plasma total thiols, respectively – were also investigated. Results: There were no differences between HD subgroups regarding haemoglobin levels. Plasma TBARS was increased in all HD patients as opposed to controls, irrespective of rHuEpo therapy. In addition, no change in antioxidant status parameters between rHuEpo-treated and -untreated patients was observed. Except for SOD, the other antioxidant indices were higher in all HD patients versus controls. Conclusions: These results suggest that (1) chronic HD patients appear to have simultaneously enhanced reactive species generation and antioxidative systems efficiency, and (2) epoietinum therapy did not change their oxidative status, at least in the absence of concomitant iron supplementation and at similar haemoglobin levels.

Elements of Mediterranean diet improve oxidative status in blood of kidney graft recipients

Patients were fully informed as to the study objectives and benefits, and provided written consent prior to enrolment. The study protocol was approved by the Committee on Human Research at the Pomeranian Medical University, Szczecin, Poland. An intensification of free-radical reactions may contribute to accelerated atherosclerosis in kidney graft recipients. We examined the effect of a Mediterranean-type diet (MD) on the oxidative status of the plasma and erythrocytes of kidney graft recipients. Two patient groups were formed: a study group consuming the MD diet and a control group with a low-fat diet. C-reactive protein levels in plasma, oleic acid C18 : 1n-9 and linoleic acid C18 : 2n-6 concentrations in triacylglycerols were determined. To determine the oxidative status, we measured the concentrations of alpha-tocopherol in plasma, the content of thiobarbituric acid-reactive species (TBARS) in plasma and erythrocytes, and the activities of superoxide dismutase, catalase and glutathione peroxidase in erythrocytes. In the MD group, the activities of erythrocyte enzymes changed significantly: those of superoxide dismutase increased (P<0.001 after 6 months), catalase decreased (P<0.001 after 6 months) and glutathione peroxidase decreased (P<0.05 after 2 months). The oleic acid content of triacylglycerols was increased (P<0.006) whereas that of linoleic acid was decreased (P<0.00005), alpha-tocopherol levels remaining unchanged. TBARS in plasma were decreased after 6 months of MD (P<0.05). No significant correlations were observed between TBARS, oleic acid, linoleic acid and alpha-tocopherol levels in plasma. MD appears to protect the erythrocytes against the action of free radicals, as reflected in the modified activities of some enzymes regulating the oxidative status of these blood cells.

Pre-exercise antioxidant enzyme activities determine the antioxidant enzyme erythrocyte response to exercise

Free radical production increases during exercise and oxidative damage occurs in several tissues. We examined the effects of three different exercise tests on the pattern of change of erythrocyte enzyme antioxidant activities. The tests were a short maximal exercise test, a submaximal prolonged exercise test and a cycling stage during competition. The participants were amateur and professional cyclists with different training statuses and different basal erythrocyte antioxidant enzyme activities. The maximal test produced no changes in the erythrocyte antioxidant enzyme activities of amateur sportsmen. The submaximal test, performed at 80% of maximal oxygen uptake, decreased erythrocyte catalase (12%), glutathione peroxidase determined with H2O2 (14%) and glutathione reductase (16%); superoxide dismutase activity increased by about 25%. The cycling stage performed by professional cyclists increased erythrocyte catalase (29%) and glutathione reductase (10%) activities. The in vivo changes in glutathione reductase activity were confirmed by in vitro measurements: hydrogen peroxide decreased and the presence of catalase increased the activity of this enzyme. In conclusion, we suggest that the different erythrocyte antioxidant enzyme responses to diverse exercise tests can be explained by the effects of hydrogen peroxide and the superoxide anion on the antioxidant enzyme activities in erythrocytes.

Effects of Some Antibiotics on Activity of Glucose-6-Phosphate Dehydrogenase from Human Erythrocytes In Vitro and Effect of Isepamicin Sulfate on Activities of Antioxidant Enzymes in Rat Erythrocytes

The purpose of this study was to investigate effects of some antibiotics on glucose-6-phosphate dehydrogenase (G6PD), antioxidant enzymes, and malondialdehyde (MDA). Initially, for in vitro studies, G6PD was purified from human erythrocyte, 9811-fold in a yield of 42.4% by using ammonium sulfate precipitation and 2′,5′ ADP-Sepharose 4B affinity gel. The purified enzyme showed a single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The effects of four different antibiotics (isepamicin sulfate, meropenem, chloramphenicol, and thiamphenicol glisinat hydrochloride) were investigated on the purified enzyme. Ki value and type of inhibition were determined by means of Lineweaver–Burk graphs and regression analysis graphs. Isepamicin sulfate inhibited the enzyme activity (I50 value, 2.1 mM; Ki value, 1.7 mM), whereas thiamphenicol glisinat hydrochloride activated the G6PD dose dependently. Other drugs showed no inhibition and activation effect. In addition, the effects of isepamicin sulfate on the activities of G6PD, glutathione reductase (GR), superoxide dismutases (SOD), glutathione peroxidase (GPx), catalase (CAT), and glutathione S-transferase (GST) and MDA contentrations were examined in Sprague-Dawley rat erythrocytes in vivo. A marked alteration in the activities of these enzymes and MDA levels may be the result of oxidative stress in the rats receiving isepamicin sulfate.