In vitro effects of melatonin on the filtrability of erythrocytes in SNP-induced oxidative stress

Erythrocyte deformability is one of the most important charactheristics of erythrocytes for an effective microcirculatory function and is affected from a number of factors, including the oxidative-damage-induced by nitric oxide (NO). This study was performed to investigate the effects of in vitro melatonin incubation on the antioxidant status and deformability of erythrocytes in sodium nitroprusside (SNP), a nitric oxide donor, induced oxidative stress. 40 blood samples taken from the adult healthy people were divided into 4 groups randomly and incubated with saline, SNP (1 mM), melatonin (MEL, 1 mM), MEL + SNP and SNP + L-NAME (5 mM) respectively. Relative filtration rate (RFR), relative filtration time (RFT) and relative resistance (Rrel) were determined as the indexes of erythrocyte filterability. In addition, malondialdehyde (MDA, as an index of lipid peroxidation) and the antioxidant activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT) were also determined in the red blood cells of all groups revealing the oxidant-antioxidant activity. RFT and the Rrel of the erythrocytes incubated with SNP increased significantly (p<0.05) whereas the RFR of the erythrocytes decreased (p<0.05) in comparison to all groups. This reduction in RFR was prevented with both L-NAME or MEL incubation. Furthermore, MEL was found to be significantly efficient in preventing the erythrocytes from lipid peroxidation in these groups. In addition, GSH-Px and SOD activities were elevated with SNP incubation reflecting the oxidative stress in erythrocytes, whereas the CAT activity remained unchanged. Melatonin has no significant effect on the GSH-Px and CAT activity but, it caused a significant decrease in SOD activity (p<0.05). These results reveal that, melatonin can protect the erythrocytes from impaired deformability in SNP-induced oxidative stress due to antioxidant effects as revealed by lipid peroxidation and antioxidant enzyme activities.     

Lipid peroxidation and deformability of red blood cells in experimental sepsis in rats: The protective effects of melatonin

Sepsis has been associated with a lipopolysaccharide (LPS) induced bacterial infection and causes biochemical, hemodynamic and physiological alterations in a system. Erythrocyte deformability is very critical for a microcirculatory system to function effectively. Hence, we were interested in examining the effects of a potent antioxidant, melatonin (Mel), on lipid peroxidation and deformability of eythrocytes in LPS-induced experimental sepsis. Male Swiss Albino rats were used in 6 groups, each group comprising of 10 animals. The first group was the control, and the other groups were administered LPS (10 mg/kg, i.p.), Mel (10 mg/kg, i.p.), LPS + L-NAME (5 mM, i.p.), Mel + LPS and Mel + LPS + L-NAME, respectively. Deformability of the RBCs decreased significantly (p < 0.05) in the LPS group in comparison to all other groups. This reduction was prevented with both L-NAME and Mel, but was not as significant as when administering L-NAME or Mel alone. This result was adversely seen in nitric oxide levels, i.e. RBCD was reduced when the NO levels were higher. Therefore in the Mel group the NO levels were reduced while the RBCD enhanced. In addition to these, as an index of lipid peroxidation, the Malondialdehyde levels were elevated in LPS groups whereas the deformability was reduced. This lipid peroxidation was suppressed by Mel and/or L-NAME significantly, where the RBCD was enhanced. These results show that, Melatonin can elevate the RBCD in experimental sepsis due to its nitric oxide scavenging activity and antioxidant effect as revealed by lipid peroxidation.     

Effects of Apple Consumption on Plasma and Erythrocyte Antioxidant Parameters in Elderly Subjects

The effects of apple consumption on plasma and erythrocyte antioxidant parameters of elderly subjects were investigated in this study. Fifteen elderly subjects (mean age 71.86 ± 4.17) participated in the study. They consumed an apple a day for 1 month. Before and after this period, fasting blood samples were obtained, and oxidant (malondialdehyde [MDA]) and antioxidant (superoxide dismutase [SOD], glutathione peroxidase [GSH-Px], catalase [CAT], and antioxidant potential [AOP]) parameters were studied. MDA and AOP levels were studied in plasma, and SOD, GSH-Px, and CAT activities and MDA levels were measured in the erythrocytes. In the erythrocytes, GSH-Px and SOD activities were found to be higher (p < .001 and p < .01), but MDA levels were lower in the second samples relative to the first ones. In the plasma, AOP value was found to be higher in the second samples relative to first ones (p < .001). No differences were found, however, between the routine blood parameters such as total cholesterol, low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, high-density-lipoprotein cholesterol, and triglyceride levels. The results show that consumption of apple leads to significant increases in the activities of some antioxidant enzymes and in the antioxidant potential values of the blood, and that decreases oxidation reactions in the body in significant amount. It is quite possible that reduced peroxidation processes owing to consumption of this fruit may play a part in some of their beneficial effects in the elderly subjects.     

Effects of apple consumption on plasma and erythrocyte antioxidant parameters in elderly subjects

The effects of apple consumption on plasma and erythrocyte antioxidant parameters of elderly subjects were investigated in this study. Fifteen elderly subjects (mean age 71.86 +/- 4.17) participated in the study. They consumed an apple a day for 1 month. Before and after this period, fasting blood samples were obtained, and oxidant (malondialdehyde [MDA]) and antioxidant (superoxide dismutase [SOD], glutathione peroxidase [GSH-Px], catalase [CAT], and antioxidant potential [AOP]) parameters were studied. MDA and AOP levels were studied in plasma, and SOD, GSH-Px, and CAT activities and MDA levels were measured in the erythrocytes. In the erythrocytes, GSH-Px and SOD activities were found to be higher (p < .001 and p < .01), but MDA levels were lower in the second samples relative to the first ones. In the plasma, AOP value was found to be higher in the second samples relative to first ones (p < .001). No differences were found, however, between the routine blood parameters such as total cholesterol, low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, high-density-lipoprotein cholesterol, and triglyceride levels. The results show that consumption of apple leads to significant increases in the activities of some antioxidant enzymes and in the antioxidant potential values of the blood, and that decreases oxidation reactions in the body in significant amount. It is quite possible that reduced peroxidation processes owing to consumption of this fruit may play a part in some of their beneficial effects in the elderly subjects.     

Asymmetric dimethylarginine reduced erythrocyte deformability in streptozotocin-induced diabetic rats

To investigate the effect of asymmetric dimethylarginine on erythrocyte deformability in streptozotocin-induced diabetic rats, a single intraperitoneal injection of streptozotocin (STZ, 65 mg/kg) in male Sprague-Dawley rats was carried out to induce diabetes and normal erythrocytes were incubated with asymmetric dimethylarginine or aortic rings from diabetic rats in the presence of L-arginine or vitamin E. We found that erythrocyte deformability was significantly decreased in diabetic rats. The levels of asymmetric dimethylarginine in plasma and erythrocytes of diabetic rats were elevated significantly from 2-week diabetic duration to 8-week diabetic duration. Nitric oxide in erythrocytes was decreased at 8-week diabetic duration while plasma nitric oxide remained unchanged all along. The content of malondialdehyde in erythrocytes of diabetic rats was increased. After incubation of erythrocytes with asymmetric dimethylarginine (10(-6) M) for 30 min, erythrocyte deformability and nitric oxide level in erythrocytes were decreased markedly. Reactive oxygen species and malondialdehyde production in erythrocytes were promoted by asymmetric dimethylarginine. Both L-arginine and vitamin E reversed the effects of asymmetric dimethylarginine. After incubation of erythrocytes with aortic rings from diabetic rats, erythrocyte deformability was decreased, which was attenuated by L-arginine. These results indicated that reduction of erythrocyte deformability in diabetic rats was associated with promoted oxidant stress as well as impaired nitric oxide synthesis by elevation of asymmetric dimethylarginine.     

外源性一氧化氮对旋毛虫感染小鼠抗氧化能力的影响

目的探讨外源性NO供体亚硝基铁氰化钠(SNP)对旋毛虫病小鼠肝脏、外周血中抗氧化酶活性及脂质氧化的影响。方法采用消化法分离旋毛虫肌幼虫,感染BALB/c小鼠,400条/只。42 d后,收集感染鼠及正常小鼠外周血、肝脏。设A组(感染鼠肝脏匀浆物+SNP)、B组(正常鼠肝脏匀浆物+SNP)、C组(感染鼠外周血+SNP)、D组(正常鼠外周血+SNP)。每组内设5个SNP反应终浓度,分别为0(空白对照)、2、5、10、30μmol/L,37℃反应30 min,测定各组超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)及脂质氧化(MDA)含量。结果与正常鼠相比,旋毛虫感染鼠肝脏、外周血中SOD、CAT、GSH-Px活性上升,MDA含量增加,差异均有统计学意义(P均0.05);在A、B组中,10、30μmol/L SNP作用下SOD、CAT、GSH-Px活性较空白对照降低(P均0.05);与2~30μmol/L SNP反应后,MDA含量较空白对照明显升高(P均0.05)。在C、D组中,30μmol/LSNP作用下SOD、CAT、GSH-Px活性显著下降,MDA浓度升高,与空白对照比较差异均有统计学意义(P均0.01)。在2~30μmol/L浓度区间,SNP浓度与旋毛虫感染鼠肝脏、外周血中SOD、CAT、GSH-Px活性呈负相关(r肝SOD=-0.901,r肝CAT=-0.802,r肝GSH-Px=-0.847,r血SOD=-0.899,r血CAT=-0.685,r血GSH-Px=-0.635,P均0.05),与MDA含量呈正相关(r肝MDA=0.697,r血MDA=0.764,P均0.05)。结论旋毛虫感染可致小鼠肝脏、外周血中活性氧自由基产生增加,SOD、CAT、GSH-Px活性升高;外源性NO可降低旋毛虫感染小鼠SOD、CAT、GSH-Px活性,抑制小鼠的抗氧化能力。     

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.     

The antioxidative defense in asthma.

Asthma is a disease characterized by chronic airway inflammation. Generation of oxygen free radicals by activated inflammatory cells produces many of the pathophysiologic changes associated with asthma and may contribute to its pathogenesis. However, the activities of antioxidant enzymes and their relation with asthma have not been well defined. This study was performed to examine the activities of major intracellular antioxidants in mild asthmatic patients. Twelve asymptomatic mild asthmatic patients who never used any antiasthma medication and 13 age- and sex-matched healthy control subjects were selected. The activities of erythrocyte antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), and glutathione-peroxidase (GSH-Px) were measured spectrophotometrically. The mean SOD activity of asthmatic patients was found to be significantly lower than that of the controls (p < 0.05). There was no significant difference in CAT and GSH-Px activities between patients and controls (p > 0.05). Although the mechanisms underlying the association between asthma and antioxidant system are unclear, according to our findings, decreased antioxidant protection may contribute to the pathogenesis of mild asthma.     

Oxidant/antioxidant status in men with Behçet’s disease

Behçet’s disease (BD) is a chronic, progressive disorder that affects many systems of the body including the eye. The aim of this study was to assess whether the increase in oxidative stress in the affected tissues is reflected by lipid peroxidation and to check for alterations in antioxidants and antioxidant enzyme activities in patients with BD. Erythrocyte antioxidant potential (AOP), glutathione (GSH) and GSH-dependent enzymes (glutathione peroxidase (GSH-Px), glutathione reductase (GRD) and glutathione-S-transferase (GST), catalase (CAT), Cu–Zn superoxide dismutase (Cu–Zn SOD) activities, malondialdehyde (MDA) and some trace elements (zinc, Zn; copper, Cu; manganese, Mn) levels in men with BD. Erythrocyte CAT, GSH-Px activities, MDA, GSH, AOP and serum Zn values were significantly lower in patients with BD than in the control group. However, erythrocyte Cu–Zn SOD, GRD activities, erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP) and Cu values were significantly higher in patients with BD than in the control group, but GST activity and serum Mn values were unchanged. In conclusion, our results confirm the presence of oxidative stress in patients with BD and suggest that the severity of BD may arise from impaired antioxidant mechanisms. Therapy with antioxidants may lead to the increase in the antioxidant defense system and thus improvement in clinical symptoms.     

Modulation of density-fractionated RBC deformability by nitric oxide

The role of nitric oxide (NO) in maintaining normal mechanical behavior of red blood cell (RBC) has been previously demonstrated. The effects of NO donor and NOS inhibitor on the mechanical properties of density fractionated RBC were tested in this study. A non-specific NOS inhibitor, N-omega-nitro-L-arginine methyl ester (L-NAME) at a concentration of 10(-3) M and sodium nitroprusside (SNP), a nitric oxide donor at a concentration of 10(-6) M was added to blood samples with hematocrit adjusted to 0.4 l/l and RBC deformability was measured by an ektacytometer in the density fractionated RBC after one hour incubation at 37 degrees C. There was no significant effect of the NO donor SNP on cellular deformability in the older (denser) RBC fraction in contrast with the younger (least dense) fraction. Alternatively, the sensitivity of cellular deformability to competitive NOS inhibition by L-NAME was greater in the older fraction. These findings suggest that older RBC are characterized by diminished internal NO synthesis and are also less sensitive to external NO indicating that the target mechanisms for NO may also be deteriorated.     

Food restriction in female Wistar rats: V. Lipid peroxidation and antioxidant enzymes in the liver

The activities of antioxidant enzymes as well as the levels of basal and enzyme induced peroxidation have been investigated in liver of female Wistar undernourished rats. Food restriction was applied starting from the age of 3.5 months by feeding the animals on every-other-day schedule (EOD). Diet restriction prevented the age-dependent increase of basal and enzyme induced lipid peroxidation in both mitochondrial and microsomal liver membrane preparations. The activities of antioxidant enzyme, i.e. superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) of liver decreased during aging in ad libitum fed rats. In the diet conditioned animals, a small increase of SOD and a complete recovery of CAT activities were observed. Present data support that food restriction improved the protection against peroxidation, and this may be in close relationship with the life prolonging effect of such a treatment.     

Role of NO pathway, calcium and potassium channels in the peripheral pulmonary vascular tone in dogs.

Because hypoxic pulmonary vasoconstriction occurs mainly in the small pulmonary arteries, the authors investigated the effects of drugs acting on the nitric oxide (NO) pathway and the calcium and potassium channels in the peripheral pulmonary circulation, without interference with the overall pulmonary or systemic circulation. Mixed venous blood was infused in wedged areas to study the pressure/flow relationship and to compute peripheral pulmonary vascular resistance (PPVR). The authors studied the effects of Nomega-nitro-L-arginine methyl ester (L-NAME), an NO synthase inhibitor, sodium nitroprusside (SNP, an NO donor), the calcium channel blockers verapamil, nifedipine and nicardipine, and the potassium channel opener levcromakalim, during normoxia and acute mild normocapnic hypoxia. In the peripheral pulmonary circulation, L-NAME caused an increase in PPVR during normoxia (+95%; p<0.001) and hypoxia (+60%; p<0.01). Following the increase by L-NAME, SNP decreased PPVR during normoxia (-24%; p<0.05) and hypoxia (-23%; p<0.05). Verapamil, nifedipine and nicardipine did not modify PPVR during normoxia but during hypoxia they decreased PPVR (-28%, nonsignificant; -27%, p<0.01 and -33%, p<0.05, respectively). Levcromakalim did not modify PPVR during normoxia or hypoxia. In conclusion, the nitric oxide pathway and voltage-dependent calcium channels, and not adenosine triphosphate sensitive potassium channels, play an important role in the control of peripheral pulmonary circulation in dogs.     

Alteration in systemic markers of oxidative and antioxidative status in Tunisian patients with asthma: relationships with clinical severity and airflow limitation

Objective: This study aims to determine the systemic oxidant-antioxidant status in Tunisian patients with asthma. Methods: We evaluated the levels of malondialdehyde (MDA) as thiobarbituric acid complexes, total protein carbonyls (PCs) and advanced oxidation protein products (AOPP). The levels of total thiols, protein sulfhydryls, glutathione (GSH), together with hydrogen peroxide, ascorbic acid, iron and total antioxidant status (TAS) were colorimetrically estimated. Glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD) activities were assessed in plasma and erythrocytes by spectrophotometry. We also determined the levels of nitric oxide (NO) and peroxynitrite in plasma from asthmatic patients and healthy controls. The volume of fractionated exhaled NO (Fe_NO) was evaluated by the Medisoft HypAir method. Estimation of DNA damage was determined using the comet assay. Results: Asthmatic patients showed increased levels of MDA in comparison to healthy controls (p?<?0.001), while no significant difference was found in protein carbonyls (p?=?0.79) and AOPP (p?=?0.98). Patients with asthma also had significantly lower levels of total thiols (355.9?±?15.72 versus 667.9?±?22.65, p?<?0.001), protein sulfhydryls (333.99?±?16.41 versus 591.95?±?24.28, p?<?0.001) and glutathione (p?<?0.001). They also showed decreased GSH-Px activity (p?<?0.001), whereas no significant differences in measurements of catalase and SOD enzyme activities were observed between the two groups (respectively, p?=?0.06 and p?=?0.55). In addition, ascorbic acid and nitric oxide levels were decreased in asthmatics in comparison to controls (p?<?0.01). Conclusions: Our findings highlight that oxidative stress and defective anti-oxidative status are major alterations in Tunisian patients with asthma.     

Malondialdehyde: a possible marker of ageing

BACKGROUND: Numerous recent studies have suggested that oxidative damage may be important in the ageing process, and lipid peroxidation is an important biological consequence of oxidative cellular damage. OBJECTIVE: The aim of this work was to analyze the activities of the two protective enzymes, superoxide dismutase (SOD) and catalase (CAT), and the levels of malondialdehyde (MDA) to examine the relationship between the ageing process and defence antioxidant and lipid peroxidation. METHOD: SOD activity was measured in red blood cells using the Minami and Yoshikawa method; CAT activity was measured in hemolysates by the Aebi method, and MDA levels were measured in erythrocytes by high-performance liquid chromatography. RESULTS: SOD activity shows statistically significant differences between newborns and the rest of the sample (ANOVA p < 0.001; Student-Newman-Keuls test p < 0.001). CAT activity did not show significant differences between the age groups. We observed statistically significant differences in MDA levels between the different groups (ANOVA p < 0.001; Student-Newman-Keuls test p < 0.05). In the regression analysis and rectilinear/curvilinear adjustment compared to age, SOD and CAT showed coefficients close to zero (SOD linear = 0.16; SOD exponential = 0.15; CAT linear = 0.056; CAT exponential = 0.068), indicating in that way their independence from age. Only MDA obtained a regression coefficient superior to 0.75 (p < 0.05). The best adjustment was reached through an exponential expression, giving the following parametric relation: MDA = 103.117e(0.0021.AGE). No statistically significant variation in SOD and CAT activity and MDA levels, related to sex could be demonstrated. CONCLUSIONS: Our data show that old age is associated with an increase in systemic oxidative stress.     

Effects of melatonin or acetylsalicylic acid on gastric oxidative stress after bile duct ligation in rats

Background Antioxidant enzyme activities decrease after bile duct ligation. The aim of this study was to assess the effect of melatonin and acetylsalicylic acid on antioxidant enzyme activities in gastric oxidative stress induced by bile duct ligation. Methods Sixty-four animals were divided into eight groups of eight rats each. Male Sprague-Dawley rats were subjected to either a sham operation or common bile duct ligation (BDL) before treatment with melatonin (MEL) or acetylsalicylic acid (ASA). Gastric superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activities, and malondialdehyde (MDA) and nitric oxide (NO) levels were determined by spectrophotometers and evaluated. Results Our results indicated that BDL caused a significant increase in lipid peroxidation, whereas coadministration of MEL with ASA significantly decreased MDA and NO levels in BDL rats. Moreover, coadministration of MEL and ASA increased antioxidant enzyme activities after the BDL, and these increases were statistically significant for CAT and GPx. On the other hand, the increase in SOD activity was not significant. Conclusions Melatonin administration, either alone or together with acetylsalicylic acid, decreases lipid peroxidation and increases antioxidant enzyme activities in gastric tissues of rats after bile duct ligation. ASA administration, however, either alone or with a vehicle, increases lipid peroxidation and decreases antioxidant enzyme activities.     

Antioxidant enzyme activities in healthy Chinese adults: influence of age, gender and smoking

OBJECTIVE: Specific antioxidant enzymes play a vital role in regulating and maintaining oxidant species. The aim of this study was to determine these antioxidant enzyme activities (i.e. catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx)) in erythrocytes from a group of healthy Chinese subjects and to study the influence of age, gender and smoking habits on the enzyme activities. METHODOLOGY: Chinese healthy subjects (n = 276) were grouped according to their age range, gender differences and smoking habits. Antioxidant enzyme activities were measured spectrophotometrically using standard kinetic methods. RESULTS: There was a significant decrease in erythrocyte GPx activity in ever-smokers compared with non-smokers (47.10 +/- 1.33 mU/g haemoglobin (Hb) vs. 51.41 +/- 1.64 mU/g Hb, P < 0.05). Age-related significant increases in erythrocyte CAT and SOD activities were found in non-smokers but not in ever-smokers. There was no age-related difference in erythrocyte GPx activity in either non-smokers or ever-smokers. Among those >60 years old, erythrocyte CAT and GPx activities were significantly lower in ever-smokers than in non-smokers (29.70 +/- 3.07 mU/g Hb vs. 41.63 +/- 4.92 mU/g Hb (P < 0.05), and 47.55 +/- 2.00 mU/g Hb vs. 55.30 +/- 3.60 mU/g Hb (P < 0.05), respectively). It was also found that females had higher erythrocyte GPx activity than males but this difference did not reach significance in non-smokers. CONCLUSION: From the results of this study, it is concluded that oxidative stress seems to be present in elderly ever-smokers among the Chinese population.     

Oxidative stress in portal hypertension-induced rats with particular emphasis on nitric oxide and trace metals

AIM: To investigate the oxidative-stress-related changes in rats with portal hypertension with particular emphasis on nitric oxide (NO) and trace metals. METHODS: Cirrhosis was induced by partial portal vein ligation (PVL) in Wistar rats. The lipid peroxidation marker (malondialdehyde, MDA), antioxidant defense enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and agents known to have antioxidant features including nitric oxide (NO), zinc (Zn), copper (Cu) were determined both in serum and in liver tissue at 4 wk after surgery in PVL and sham-operated rats. Portal pressure of all experimental animals was measured. MDA was detected by thiobarbituric acid reactivity assay. SOD activity was determined by inhibition of nitroblue tetrazolium reduction with xanthine/xanthine oxidase used as a superoxide generator. CAT activity was determined by the breakdown of hydrogen peroxide. GSH concentrations were measured by using metaphosphoric acid for protein precipitation and 5'-5'-dithio-bis-2-nitrobenzoic acid for color development. NO was detected by the Griess method after reduction of nitrate to nitrite with nitrate reductase, and the concentrations of Zn and Cu were measured by a Shimadzu 680 AA atomic absorption spectrometer. Histopathological confirmation was done under light microscope. Statistical analyses were done by Student's t-test, and significance of the difference was tested by the unpaired Mann-Whitney test. P<0.05 was considered statistically significant. RESULTS: Histopathological studies confirmed PVL-induced cirrhotic changes. There was a statistically significant difference in portal pressure between PVL and control groups (P<0.001). The results showed significant increases in the levels of MDA and NO in both tissue and serum (P<0.05 and P<0.001, respectively in tissue; P<0.001 for each in serum), and Zn only in tissue (P<0.001) in rats with PVL compared with sham-operated rats. Besides, PVL rats exhibited reduced plasma and tissue GSH, CAT, SOD (P<0.001 for each). Serum and tissue Cu concentration did not change. CONCLUSION: Our findings suggest that PVL in rats induces important biochemical and molecular changes related to oxidative stress in the liver.     

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.     

Effects of oestradiol and oestroprogestin on erythrocyte antioxidative enzyme system activity in postmenopausal women

OBJECTIVE: Data concerning the relationship between sex steroid hormones and the cellular antioxidative enzyme system are controversial. We investigated the effects of oestradiol deficiency after menopause and the influence of transdermal oestradiol therapy (ET) and hormonal (oestradiol plus medroxyprogesterone) replacement therapy (HT) on erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT). GSH and selenium (Se) concentrations were also estimated. Serum lipid peroxide (LPO) levels were measured as an indicator of free-radical production and lipid peroxidation. PATIENTS: The study group consisted of 80 postmenopausal women, divided into two subgroups: 26 women with surgically induced menopause (ET1) and 54 women with physiological menopause (HT1). Forty premenopausal healthy volunteers were controls (C group). RESULTS: LPO was higher in postmenopausal women and decreased after both ET and HT. GSH-Px and GSH were lower in the postmenopausal groups but increased significantly after both types of therapy. Se concentrations did not differ significantly among the groups. CAT activities were similar in all groups and decreased after ET and HT. SOD activities in postmenopausal women were similar to those in the C group and did not change significantly after treatment. CONCLUSIONS: The administration of natural oestrogens to postmenopausal women diminishes oxidative stress and increases antioxidative cell potency.     

Lack of nitric oxide mediation of flow-dependent arteriolar dilation in type I diabetes is restored by sepiapterin

The mechanisms leading to microangiopathy in diabetes mellitus have still not been clearly elucidated. We hypothesized that type I diabetes mellitus affects the endothelium and alters flow-dependent dilation of arterioles, an important mechanism involved in local regulation of blood flow. Isolated, pressurized gracilis muscle arterioles (inside diameter approximately 150 microm at 80 mm Hg) from rats with streptozotocin (STZ)-induced diabetes mellitus exhibited reduced dilations induced by increases in perfusate flow compared to those of normal rats (plasma glucose: 25.7 +/- 0.7 vs. 6.4 +/- 0.5 mmol/l; maximum increase in diameter: 15 +/- 4 vs. 31+/- 3 microm, p < 0.05). In control arterioles, both nitric oxide (NO) and prostaglandins mediated the flow-dependent dilation, whereas flow-induced dilations of diabetic arterioles were unaffected by N(omega)-nitro-L-arginine methyl ester (L-NAME) and were abolished by indomethacin. Sepiapterin - precursor of the endothelial NO synthase (eNOS) cofactor tetrahydrobiopterin (BH(4)) - restored the L-NAME-sensitive portion of flow-dependent dilations of diabetic arterioles. Furthermore, depletion of BH(4) by 2,4-diamino-6-hydroxypyrimidine (DAHP) in control arterioles also resulted in reduced flow-dependent dilations, which were restored by intraluminal sepiapterin [but not with superoxide dismutase (SOD) plus catalase (CAT) (SOD+CAT)] and then could be inhibited by L-NAME. Dilations induced by the NO donor sodium nitroprusside (SNP) were unaffected by L-NAME in diabetes mellitus arterioles or when eNOS was activated by intraluminal flow in DAHP-treated arterioles (with or without SOD+CAT). In contrast, pyrogallol (known to produce reactive oxygen species) substantially reduced acetylcholine- and SNP-induced dilation in a SOD+CAT-reversible manner. Collectively, these findings suggest that in diabetic arterioles, due to the reduced bioavailability of BH(4), the synthesis of NO by eNOS is limited, resulting in a reduced flow-induced dilation, a mechanism that may also be responsible for the development of diabetic microangiopathy and exacerbation of other vascular diseases.