Determination Of Catalase Activity Research Articles

Comparison of Oxygen Electrode Chronoamperometry and Spectrophotometry for Determination of Catalase Activity

Catalase is a key antioxidative enzyme, and a deficiency or malfunction of catalase is hypothesized to be related to various diseases. To investigate catalase activity, it is important to use reliable methods and experimental protocols enabling consistent fallouts. One major problem, however, is that the activity values obtained with different techniques and procedures can vary to a large extent. The aim of this work was to identify experimental conditions that provide similar catalase activity values with two different methods based on either spectrophotometry or chronoamperometry. The investigated parameters include the concentration of catalase and its substrate (H2O2), as well as the effect of deoxygenation of the catalase medium by nitrogen (N2). Within the frame of investigated conditions, we show that spectrophotometry is strongly affected by the catalase concentration, whereas chronoamperometry is shown to be more dependent on the substrate concentration. Deoxygenation leads to elevated catalase activity values in the case of chronoamperometry, whereas it shows no influence on the results obtained with spectrophotometry. In particular, in the case of low substrate concentrations (i.e., low catalase reaction rates), higher and more accurate results are obtained with deoxygenation in the case of chronoamperometry measurements due to minimized oxygen escape. The effect of deoxygenation, giving rise to elevated catalase activity values, however, is not statistically significant at high substrate concentrations, implying that the protocol can be simplified by excluding this step as long as the other parameters are optimized. Finally, by comparing the two methods at different experimental conditions, we identified protocols resulting in similar results, i.e., 10 mM H2O2 and catalase activity of 4–5 U/mL. Based on this work, improved consistency of catalase activity data obtained with different methodologies and in different labs is expected.

Non-Destructive Hyperspectral Imaging for Rapid Determination of Catalase Activity and Ageing Visualization of Wheat Stored for Different Durations.

(1) In order to accurately judge the new maturity of wheat and better serve the collection, storage, processing and utilization of wheat, it is urgent to explore a fast, convenient and non-destructively technology. (2) Methods: Catalase activity (CAT) is an important index to evaluate the ageing of wheat. In this study, hyperspectral imaging technology (850-1700 nm) combined with a BP neural network (BPNN) and a support vector machine (SVM) were used to establish a quantitative prediction model for the CAT of wheat with the classification of the ageing of wheat based on different storage durations. (3) Results: The results showed that the model of 1ST-SVM based on the full-band spectral data had the best prediction performance (R2 = 0.9689). The SPA extracted eleven characteristic bands as the optimal wavelengths, and the established model of MSC-SPA-SVM showed the best prediction result with R2 = 0.9664. (4) Conclusions: The model of MSC-SPA-SVM was used to visualize the CAT distribution of wheat ageing. In conclusion, hyperspectral imaging technology can be used to determine the CAT content and evaluate wheat ageing, rapidly and non-destructively.

Moderate ethanol exposure during early ontogeny of the rat alters respiratory plasticity, ultrasonic distress vocalizations, increases brain catalase activity, and acetaldehyde-mediated ethanol intake.

Early ontogeny of the rat (late gestation and postnatal first week) is a sensitive period to ethanol's positive reinforcing effects and its detrimental effects on respiratory plasticity. Recent studies show that acetaldehyde, the first ethanol metabolite, plays a key role in the modulation of ethanol motivational effects. Ethanol brain metabolization into acetaldehyde via the catalase system appears critical in modulating ethanol positive reinforcing consequences. Catalase system activity peak levels occur early in the ontogeny. Yet, the role of ethanol-derived acetaldehyde during the late gestational period on respiration response, ultrasonic vocalizations (USVs), and ethanol intake during the first week of the rat remains poorly explored. In the present study, pregnant rats were given a subcutaneous injection of an acetaldehyde-sequestering agent (D-penicillamine, 50 mg/kg) or saline (0.9% NaCl), 30 min prior to an intragastric administration of ethanol (2.0 g/kg) or water (vehicle) on gestational days 17-20. Respiration rates (breaths/min) and apneic episodes in a whole-body plethysmograph were registered on postnatal days (PDs) 2 and 4, while simultaneously pups received milk or ethanol infusions for 40-min in an artificial lactation test. Each intake test was followed by a 5-min long USVs emission record. On PD 8, immediately after pups completed a 15-min ethanol intake test, brain samples were collected and kept frozen for catalase activity determination. Results indicated that a moderate experience with ethanol during the late gestational period disrupted breathing plasticity, increased ethanol intake, as well brain catalase activity. Animals postnatally exposed to ethanol increased their ethanol intake and exerted differential affective reactions on USVs and apneic episodes depending on whether the experience with ethanol occur prenatal or postnatally. Under the present experimental conditions, we failed to observe, a clear role of acetaldehyde mediating ethanol's effects on respiratory plasticity or affective states, nevertheless gestational acetaldehyde was of crucial importance in determining subsequent ethanol intake affinity. As a whole, results emphasize the importance of considering the participation of acetaldehyde in fetal programming processes derived from a brief moderate ethanol experience early in development, which in turn, argues against "safe or harmless" ethanol levels of exposure.

Antioxidant effect of cortexin, cerebrolysin and actovegin in rats with chronic cerebrovascular insufficiency

To compare the antioxidant effects of cortexin, cerebrolysin and actovegin in rats with chronic brain ischemia. Chronic brain ischemia was modeled in male rats by 50% stenosis of the common carotid arteries. Forty days after surgery, the animals received 2 ten-day courses of therapy, separated by a break of 10 days. Placebo, cortexin (0.3, 1 and 3 mg/kg), cerebrolysin (0.8, 2.5 and 7.5 ml/kg) and actovegin (5 ml/kg) were administered to animals as treatment. The concentration of malondialdehyde (MDA) in the homogenates was determined by the reaction with thiobarbituric acid, the concentration of reduced glutathione was determined by the reduction reaction of 5.5-dithiobis- (2-nitrobenzoic acid); determination of catalase activity, as well as the content of lactate and pyruvate, by commercially available reagent kits. The activity of superoxide dismutase (SOD) was determined by the photometric method based on an assessment of the degree of inhibition of the epinephrine oxidation reaction. All reactions were carried out in triplicates. Modeling of chronic brain ischemia led to the statistically significant decrease in the content of lactate and pyruvate (p<0.001, when compared with the control group), which was not accompanied by a significant decrease in their ratio (p>0.05), as well as to the decrease in SOD, catalase activity, restored glutathione and increase in MDA concentrations. Compared with the control group, in the groups that received cortexin at a dose of 3 mg/kg/day, cerebrolysin at a dose of 7.5 ml/kg/day and actovegin at a dose of 5 ml/kg/day, there were an increase in the content of lactate and pyruvate (without a significant change in their ratio), restoration of glutathione levels and the activity of SOD and, to a lesser extent, catalase, combined with a decrease in the concentration of MDA. Course administration of cortexin (3 mg/kg), cerebrolysin (7.5 ml/kg) and, to a lesser extent, actovegin (5 ml/kg) has a positive effect on the state of the antioxidant system of the brain in rats with chronic brain ischemia.

Supplementation with l-glutathione improves oxidative status and reduces protein nitration in myenteric neurons in the jejunum in diabetic Rattus norvegicus

Diabetes mellitus is a syndrome with multiple etiologies, characterized by chronic hyperglycemia that increases the production of reactive oxygen species and decreases antioxidant defenses. The present study evaluated oxidative stress parameters and protein nitration in myenteric neurons in the jejunum in diabetic rats supplemented with l-glutathione. Rats (90 days of age) were distributed into four groups (n = 6/group): normoglycemic (N), normoglycemic supplemented with l-glutathione (NGT), diabetic (D), and diabetic supplemented with l-glutathione (DGT). At 210 days of age, the animals were sacrificed, and the jejunum was collected, washed, and subjected to various procedures: tert-butyl hydroperoxide chemiluminescence (CL), determination of total antioxidant capacity (TAC), determination of catalase activity, quantification of nitric oxide (NO), and double-labeling of HuC/D-immunoreactive myenteric neurons and nitrotyrosine (3-NT). Diabetes increased oxidative stress in the jejunum in the D group, reflected by increases in lipid peroxidation, TAC, catalase activity, and NO. The D group exhibited an increase in the percentage of myenteric neurons that were double-labeled with 3-NT. Supplementation with l-glutathione did not cause differences in the average CL curves between the D and DGT groups, but reductions of TAC and catalase activity were observed. Supplementation with l-glutathione promoted a reduction of neurons that contained 3-NT in the DGT group. Diabetes mellitus promoted oxidative stress in the jejunum, and supplementation with l-glutathione improved oxidative status by preventing protein nitration in myenteric neurons in diabetic animals that received supplementation.

Juçara pulp supplementation improves glucose tolerance in mice.

BackgroundThe consumption of hyperlipidic and hypercaloric diet is considered a major factor to promote obesity and the consumption of food with antioxidant properties, like Juçara (Euterpe edulis Mart), could be a tool to prevent the deleterious effect of high white adipose deposition. The aim of the present study was to evaluate the effect of administration of juçara pulp in mice fed a high-fat, high-calorie diet on glucose tolerance and adipose tissue inflammatory status.MethodsMice were distributed into the following groups: control diet; control diet plus 0.5 % of juçara; control diet plus 2 % of juçara; hypercaloric and hyperlipidic diet; hypercaloric and hyperlipidic diet plus 0.5 % of juçara and hypercaloric and hyperlipidic diet plus 2 % of juçara. Treatments started when mice were 8 weeks old and carried on for a total period of 10 weeks. The serum glucose, triacylglycerol, total cholesterol, insulin, adiponectin, lipopolysaccharides and free fatty acids concentrations were measured. Oral glucose tolerance test was performed. TNF-α, IL-6, and IL-10 protein level were determined by ELISA on mesenteric and epididymal white adipose tissues. Determination of catalase activity was realized in the same tissues. Data were analysed using one-way analysis of variance and post hoc analysis was performed with the Tukey’s test.ResultsThe addition of 0.5 % juçara improved glycemic response in animals that consumed normocaloric as well as hypercaloric and hyperlipidic diets (HC). Supplementation with 0.5 and 2 % did not change the body composition of animals that received the HC diet; however, the animals fed the normocaloric diet with 2 % juçara gained body mass. An intake of 2 % juçara in the HC diet promoted a reduction of catalase activity and IL-10 level in epididymal adipose tissue.ConclusionsThese results suggest that with the administration of 0.5 % juçara, the beneficial effects of polyphenols overcome the deleterious effects of macronutrient composition of juçara, whereas with the administration of 2 % juçara promotes damage by the composition of the fruit and overshadows the beneficial effects of polyphenols on glucose metabolism. On the other hand, higher juçara supplementation improves the inflammatory status targeted by the HC diet.

Development of method for the mineral water catalase activity determination

Introduction. The availability in Ukraine of diversified unique natural mineral water (MW) resources does necessitate a detailed study of that water properties in order of its widespread use in the balneological and extra-resort practice, considering the MW as an important factor of population health preserving and improving [1]. The mineral water rational use is largely determined by its physical and chemical composition, sanitary and microbiological status, the presence of autochthonous microorganisms and those microorganisms’ ability to influence the water organoleptic characteristics and biological properties. In MW practical use the key importance is tribute to controlling the water quality parameters for the prediction of water safety degree and the detection of biological exposure. The MW biological effect depends on the mineralization degree, chemical composition, presence of biologically active components and compounds, as well as on their microbial cenosis’ metabolic products. Analyzing the mineral water microorganisms’ list we reveal their active biochemical effect [1]. The numerous microorganisms contributing to the mineral water’s autochthonous microflora do often include significant concentrations in saprophytic microorganisms producing the catalase as an enzyme of oxidoreductases class, a heme-containing chromoproteid making part of the cell’s antioxidant system and acting as an antiperoxidant protector agent [2]. Peroxide mechanisms may occur in the brain and in other tissues during aging, when exposure to poisons and toxins, when cerebral apoplexy, at nervous system injuries, and others processes. The biological role of catalase refers to the complex enzymatic protection of cell membranes against hydrogen peroxide-caused degradation. The catalase does metabolize the hydrogen peroxide, preventing its accumulation in the cell through producing water and oxygen. The most relevant catalase application relates to the treatment of diseases requiring an effective antioxidant protector: cardiovascular, rheumatic diseases, allergies, central and autonomic nervous systems’ diseases, gastrointestinal diseases, oncology, plastic surgery, etc. [2]. Given the important physiological role of catalase, it is necessary to determine the mineral water’s enzymatic activity. At present the methodology for MW enzymatic activity determination is still absent, so such methods’ elaboration problem is top priority one. Analysis of recent researches and publications. Methods for catalase activity quantitative determination are based on the estimation of enzyme-cleaved hydrogen peroxide quantity when enzymatic activity is assessed by the catalase index. The reference sources describe several methods of catalase activity assessment, but these methods relate to the biological objects (plasma, serum, etc.). To develop methods for determining the MW catalase activity we proceed to review the available approaches. Known is the enzymatic activity determining method by Bach and Oparin based onto titration [3], through assessing the quantity of hydrogen peroxide decomposed during incubation with the enzyme. The amount of hydrogen peroxide in the reaction mixture is assessed by titration with a Potassium permanganate solution in an acidic environment. However, this method has such drawbacks as a high labour intensity, results’ poor reproducibility and low sensitivity.

Determination of Catalase Activity and Estimation of Zn, Mn and Fe in Moss Samples Collected from Heavy Traffic Areas

Moss Physcomitriumpyriforme and Octoblepharumalbidum samples were collected from some gardens and Monument areas and some Heavy Traffic areas. Samples were collected from soils and moist brick walls and analysed for determination of elements Zn, Mn and Fe. Samples collected from Garden and Monument areas treated as Control. Samples collected from Heavy Traffic areas showed higher level of elements in comparison to the samples collected from Garden and Monument sites. Higher content of Zinc, Manganese and Iron was found in the Heavy Traffic areas as compared to the Garden and monument areas. A parameter, catalase Activity has also been studied by using particular method to determine the effect of pollution on the metabolism of species.

DEVELOPMENT OF A NEW BIOSENSOR FOR DETERMINATION OF CATALASE ACTIVITY

Catalase is one of the major antioxidant enzymes that catalyzes the hydrolysis of H2O2. The aim of this study was to suggest a new method for the assay of catalase activity. For this purpose, an amperometric biosensor based on glucose oxidase for determination of catalase activity was developed. Immobilization of glucose oxidase was made by a cross-linking method with glutaraldehyde on a Clark-type electrode (dissolved oxygen probe). Optimization and characterization properties of the biosensor were studied and determination of catalase activity in defined conditions was investigated in artificial serum solution. The results were compared with a reference method.

&lt;b&gt;Fish histopathology and catalase activity as biomarkers of the environmental quality of the industrial district on the Amazon estuary, Brazil&lt;/b&gt; - doi: 10.4025/actascibiolsci.v35i3.18032

The environment quality of an industrial district on the river Pará, Amazon estuary, Brazil, based on the assessment of histological alterations and on the determination of catalase activity of the hepatic tissue of two fish species, Plagioscion squamossissimus and Lithodoras dorsalis, is provided. Histopathological changes were evaluated semi-quantitatively and qualitatively. Mean Assessment Values (MAV) and Histological Alteration Index (HAI) of organ lesions were calculated for each zone under analysis, with different impact levels: Zone 1 (industrial district, with high contamination risk); Zone 2 (medium risk) and Zone 3 (minimum risk). Strong positive catalase activity and histopathological changes were reported in Zone 1. None of the specimens of either species captured in Zones 1 and 2 was healthy, whereas more than 60% of the specimens from Zone 3 presented healthy hepatic tissue. The principal alterations observed in the tissue of the two species included an increase in the number of Melanomacrophagous centers, fatty degeneration, inflammation, congestion, hepatitis and focal necrosis. The carnivorous P. squamosissimus presented higher levels of alteration than the herbivorous L. dorsalis. Results showed that local anthropogenic impacts were affecting the health of the two fish species under analysis.

Determination of catalase activity using chromogenic probe involving iso-nicotinicacidhydrazide and pyrocatechol

A biocatalatic pathway involving chromogenic probe has been proposed for the determination of catalase activity by means of iso-nicotinicacidhydrazide (INH) and pyrocatechol (PC). The assay is based on the enzymatic consumption of hydrogen peroxide using INH-PC system. The response of the catalase activity was ascertained by the rate of the reaction involving 14.10mM H(2)O(2). On addition of H(2)O(2), INH-PC indicator system formed a chromogenic product with absorbance maxima at 490 nm. Hence the activity of catalase was directly measured by the chromogenic response in the formation of the coupled product. The catalase assay was elaborated by the kinetic response of the INH-PC system. The linearity of the catalase activity and H(2)O(2) was in the range 0.2-7.0 units and 1.76-7.0mM, respectively in 3 ml solution. The catalytic efficiency and catalytic power were calculated. The Michaelis-Menten constant of INH, PC and H(2)O(2) were found to be 0.344, 0.176 and 8.82 mM, respectively. The indicator reaction was applied in the determination of catalase activity in mycelia mats and culture media.

The Use of Goosegrass (Eleusine indica) to Remediate Soil Contaminated with Petroleum

A greenhouse experiment was performed to evaluate effectiveness of goosegrass (Eleusine indica) in phytoremediation of soil contaminated with 8,247 mg kg−1 of total petroleum hydrocarbons (TPH). We determined seed germination toxicity, soil microbial viable counts, catalase activity, dehydrogenase activity (DHA), and the concentrations of TPH and 14 polycyclic aromatic hydrocarbons (PAHs) in soil and plant tissue. After 5 months, the initial level of contamination was reduced by 47% in planted soil, whereas it was only reduced by 11% in nonplanted soil. Bacterial numbers were 72 times greater in the rhizosphere treated soil than in the unvegetated treatment at the end of the study. There was no correlation between microbial counts or DHA and catalase activity, and the correlation between microbial counts and DHA was weak. Significant chemical reduction of H2O2, caused by the soil fabric, was observed in the determination of catalase activity. In case of vegetated treatment, 32% of PAHs was removed, but only 5% of PAHs was dissipated in the unvegetated pots. Gas chromatography/mass spectrometry analysis of plant tissue indicated that a low amount of PAHs (25.50 mg kg−1 dry biomass) was detected in goosegrass roots growing in the contaminated soil, and no uptake into the shoots was occurring.

Renal Tissue Damage After Experimental Pyelonephritis: Role of Anti-Oxidants and Selective Cyclooxygenase-2 Inhibitors

Purpose Our aim was to examine the effect of anti-oxidant and selective cyclooxygenase-2 inhibitor therapy given adjunct to the conventional treatment of acute pyelonephritis on renal tissue damage. Material and Methods 48 wistar rats were divided into 4 groups according to their treatment modalities which were started one day after inoculation of all rats with 0.1 ml of E.Coli(ATCC 25922 1010 cfu/ml).First group received only antibiotic treatment with ceftriaxone(50 mg/kg, IM), second and third group received L-Carnitine(500 mg/kg, IM) and Meloxicam(.mg/kg,IM) in addition to the conventional treatment, respectively. Fourth group received combination therapy(L-Carnitine and Meloxicam)in addition to group one. 3 and 7 days after E.Coli inoculation rats were sacrificed and kidney samples were obtained for histologic determination of tubular atrophy, acute and chronic inflammation, interstitial fibrosis and biochemical determination of catalase activity(CAT), total antioxidant capacity(TAC) and malondialdehyde(MDA). Results Interstitial fibrosis(p:0.06),chronic inflammation(p:0.536) and tubular atrophy(p:0.094) decreased in group 4 compared to the other groups but there was statistically significant decrease only in acute inflammation(p:0.015). In addition,if the day of nephrectomy is considered, there was again a significant decrease in acute inflammation findings in day 7 compared to day 3 in group 2,3 and 4(p:0.002). CAT significantly increased in group 2(p:0.029),group 3(p:0.02) and group 4(p:0.014) and decreased in group 1(p:0.012) in day 7. Conclusions Acute renal inflammatory injury can be prevented much more effectively by combination therapy than conventional therapy. This process is probably due to the prevention of free oxygen radical generation by anti-oxidants and inhibition of chemotaxis by selective cyclooxygenase-2 inhibitors.

Renal Tissue Damage After Experimental Pyelonephritis: Role of Anti-Oxidants and Selective Cyclooxygenase-2 Inhibitors

Purpose Our aim was to examine the effect of anti-oxidant and selective cyclooxygenase-2 inhibitor therapy given adjunct to the conventional treatment of acute pyelonephritis on renal tissue damage. Material and Methods 48 wistar rats were divided into 4 groups according to their treatment modalities which were started one day after inoculation of all rats with 0.1 ml of E.Coli (ATCC 25922 1010 cfu/ml).First group received only antibiotic treatment with ceftriaxone (50 mg/kg, IM), second and third group received L-Carnitine (500 mg/kg, IM) and Meloxicam (.mg/kg, IM) in addition to the conventional treatment, respectively. Fourth group received combination therapy (L-Carnitine and Meloxicam) in addition to group one. 3 and 7 days after E.Coli inoculation rats were sacrificed and kidney samples were obtained for histologic determination of tubular atrophy, acute and chronic inflammation, interstitial fibrosis and biochemical determination of catalase activity (CAT), total antioxidant capacity (TAC) and malondialdehyde (MDA). Results Interstitial fibrosis (p:0.06), chronic inflammation (p:0.536) and tubular atrophy (p:0.094) decreased in group 4 compared to the other groups but there was statistically significant decrease only in acute inflammation (p:0.015). In addition,if the day of nephrectomy is considered, there was again a significant decrease in acute inflammation findings in day 7 compared to day 3 in group 2,3 and 4 (p:0.002). CAT significantly increased in group 2 (p:0.029),group 3 (p:0.02) and group 4 (p:0.014) and decreased in group 1 (p:0.012) in day 7. Conclusions Acute renal inflammatory injury can be prevented much more effectively by combination therapy than conventional therapy. This process is probably due to the prevention of free oxygen radical generation by anti-oxidants and inhibition of chemotaxis by selective cyclooxygenase-2 inhibitors. Our aim was to examine the effect of anti-oxidant and selective cyclooxygenase-2 inhibitor therapy given adjunct to the conventional treatment of acute pyelonephritis on renal tissue damage. 48 wistar rats were divided into 4 groups according to their treatment modalities which were started one day after inoculation of all rats with 0.1 ml of E.Coli (ATCC 25922 1010 cfu/ml).First group received only antibiotic treatment with ceftriaxone (50 mg/kg, IM), second and third group received L-Carnitine (500 mg/kg, IM) and Meloxicam (.mg/kg, IM) in addition to the conventional treatment, respectively. Fourth group received combination therapy (L-Carnitine and Meloxicam) in addition to group one. 3 and 7 days after E.Coli inoculation rats were sacrificed and kidney samples were obtained for histologic determination of tubular atrophy, acute and chronic inflammation, interstitial fibrosis and biochemical determination of catalase activity (CAT), total antioxidant capacity (TAC) and malondialdehyde (MDA). Interstitial fibrosis (p:0.06), chronic inflammation (p:0.536) and tubular atrophy (p:0.094) decreased in group 4 compared to the other groups but there was statistically significant decrease only in acute inflammation (p:0.015). In addition,if the day of nephrectomy is considered, there was again a significant decrease in acute inflammation findings in day 7 compared to day 3 in group 2,3 and 4 (p:0.002). CAT significantly increased in group 2 (p:0.029),group 3 (p:0.02) and group 4 (p:0.014) and decreased in group 1 (p:0.012) in day 7. Acute renal inflammatory injury can be prevented much more effectively by combination therapy than conventional therapy. This process is probably due to the prevention of free oxygen radical generation by anti-oxidants and inhibition of chemotaxis by selective cyclooxygenase-2 inhibitors.

The effect of carotid stenting on rheological parameters, free radical production and platelet aggregation

Carotid artery stenting has become a possible treatment of significant carotid stenosis. The risk of stent occlusion and restenosis might be increased by abnormal rheological conditions amplified platelet aggregation and free radical production during the operation. The aim of our study was to assess the changes in hemorheological parameters, platelet aggregation, and catalase activity after endovascular treatment of carotid stenosis. 18 patients (11 men, ages 68 +/- 9 years and 7 women, ages 62 +/- 8 years) suffering from significant carotid stenosis and treated with carotid endovascular intervention were examined. Alteration in hemorheological parameters as well as epinephrine-, ADP-, and collagen-induced platelet aggregation were evaluated. Antioxidant reserve was characterized by the determination of catalase activity. The measurements were carried out directly before and after the procedure and 1, 2, 5 days and 1 month following the intervention. Preceding the operation the patients were administered a maximum dose (300 mg) of clopidogrel. Hematocrit, plasma fibrinogen concentration (PFC) and whole blood-, and plasma viscosity values (WBV and PV) significantly decreased immediately after stenting (p<0.001). By the fifth day following the intervention the PFC, WBV, PV, red blood cell (RBC) aggregation and ADP-induced platelet aggregation significantly increased (p<0.0001) compared to values measured postprocedurally. At 1 month follow-up these parameters, except whole blood viscosity, decreased significantly compared to measurements made on the 5th day. On the other hand, catalase activity showed significant elevation by the end of the first month. Hemorheological parameters and platelet aggregation showed specific changes following carotid stenting. Abnormal changes of the rheological conditions and increasing platelet activation are the most pronounced in the first week following stenting, which may lead to early stent occlusion. Oxidative stress production returned to baseline levels only by the end of the first month.

Superoxide-Dependent Cathepsin Activation Is Associated with Hypertensive Myocardial Remodeling and Represents a Target for Angiotensin II Type 1 Receptor Blocker Treatment

The elastolytic activity of cathepsins in the myocardium is implicated in hypertensive heart failure (HF). Given that reactive oxygen species are also implicated in protease activation associated with cardiac remodeling, we examined the role of the reactive oxygen species-induced cathepsin activation system in cardiac remodeling during the development of hypertensive HF. Dahl salt-sensitive hypertensive rats maintained on a high-salt diet were treated with vehicle, the cathepsin inhibitor E64d, or the angiotensin receptor blocker olmesartan from 12 to 19 weeks of age. Cathepsin expression and activity were increased in the left ventricle of HF rats; olmesartan inhibited these effects, restored the balance between elastin and collagen in the left ventricle, and suppressed degradation of the elastic lamina of coronary arteries of HF rats. Furthermore, olmesartan inhibited up-regulation of NADPH oxidase subunits and activity as well as superoxide generation. These effects of olmesartan were mimicked by E64d and were accompanied by amelioration of cardiac fibrosis. Finally, olmesartan and apocynin reduced angiotensin II-induced increases in cathepsin mRNA and protein levels in cultured rat neonatal cardiac myocytes. These data suggest that cathepsins likely trigger and promote cardiac remodeling and that blocking the angiotensin II type 1 receptor attenuates cathepsin expression and activity by inhibiting the production of superoxide by NADPH oxidase, thereby attenuating cardiac remodeling and dysfunction.

The importance of oxidative stress in pathogenesis of type 1 diabetes: Determination of catalase activity in lymphocytes of diabetic patients

Type 1 diabetes is a protoype of disease with an intensive oxidative stress. The oxidative stress means disturbing dynamic balance between prooxidants and antioxidants, either due to the increased production of the oxygen free radicals or the decreased antioxidant activity. The antioxidative enzyme catalase diminishes free radical hydrogen-peroxyde, which can be very toxic to pancreatic cells. Our study included 40 children with type 1 diabetes. We analysed the activity of enzyme catalase in lymphocytes in different phases of disease: at the beginning of diabetes, in remission period and in the later chronic course. There is a significant increase in the catalase activity during all phases of disease (p<0.00001) compared with the control group. The highest catalase activity occurs in the early course of disease (p<0.05) followed by a linear decrease and the lowest activity in chronic course. If metabolic control gets worse, the catalase activity gets higher with statistic significance at p<0.05. A higher residual beta cells secretion is associated with a lower catalase activity. Therefore, the catalase activity is in direct corelation with GHbA1 (r=0.895), and inverse correlation with C-peptide (r=-0.945). A significant increase in the catalase activity in all phases of type 1 diabetes indirectly confirms the importance of the oxidative stress in pathogenesis of disease. The activation of catalase is probably the secundary phenomenon. The fact that the catalase activity reaches its highest values at the beginning of diabetes could implicate the predictive value of catalase determination.

The effect of carotid stenting on rheological parameters, free radical production and platelet aggregation

Carotid artery stenting has become a possible treatment of significant carotid stenosis. The risk of stent occlusion and restenosis might be increased by abnormal rheological conditions amplified platelet aggregation and free radical production during the operation. The aim of this study was to assess the changes of the rheologic parameters, platelet aggregation, and oxidative stress after endovascular treatment of carotid stenosis. 18 patients (11 men, ages 68 +/- 9 years and 7 women, ages 62 +/- 8 years) suffering from significant carotid stenosis and treated with carotid endovascular intervention were examined. Alteration in hemorrheological parameters as well as epinephrine-, ADP-, and collagen-induced platelet aggregation were evaluated. Oxidative stress was characterized by the determination of catalase activity. The measurements were carried out directly before and after the procedure and 1, 2, 5 days and 1 month following the intervention. Preceding the operation the patients were administered a maximum dose (300 mg) of clopidogrel. The hematocrit, the plasma fibrinogen concentration (Pfc) and whole blood-, and plasma viscosity (Wbv and Pv) decreased significantly immediately after stenting ( p < 0.001). By the fifth day following the intervention the Pfc, Wdv, Pv, red blood cell (Rbc) aggregation and ADP-induced platelet aggregation increased significantly ( p < 0.0001) compared to values measured after the procedure. At 1 month follow-up these parameters, excepting Wbv, decreased significantly compared to measurements made on the 5th day. On the other hand, catalase activity showed significant elevation by the end of the first month. Hemorrheological parameters and platelet aggregation showed specific changes following carotid stenting. Abnormal changes of the rheological conditions and increasing platelet activation are the most pronounced in the first week following stenting, which may lead to the stent's early occlusion. Oxidative stress production returned to baseline levels only by the end of the first month.

Determination of catalase‐like activity in plants based on the amperometric monitoring of hydrogen peroxide consumption using a carbon paste electrode modied with ruthenium(IV) oxide

A carbon paste electrode containing ruthenium(IV) oxide as a modifier was tested as an effective hydrogen peroxide amperometric sensor in bulk measurements (hydrodynamic amperometry). Factors that influence its overall analytical perform ance, such as pH and the applied potential, were examined. The RuO2-modified electrode displayed high sensitivity towards hydrogen peroxide, with detection limits as low as 0.02 mm at pH 7.4 and 0.007 mM at pH 9.0. The method was applied for monitoring the decomposition of hydrogen peroxide (by catalase) in phosphate buffer of pH 7.4. The relative response of the electrode towards ascorbic acid was assessed and it was found that the selectivity of the RuO2-modified electrode towards hydrogen peroxide over ascorbic acid could be significantly improved by electro-polymerizing m-phenylenediamine on its surface prior to measurements. The RuO2-modified electrode was used for the kinetic (fixed time) determination of catalase activity in the range of 4-40 U/mL (detection limit 1.2 U/mL). The method was applied to the determination of catalase-like activity in various plant materials (recov-ery ranged from 93 to 101%, detection limit 480 U/100 g).

Precise Method for the Measurement of Catalase Activity in Honey

An improved method is reported for the determination of catalase activity in honey. We tested different dialysis membranes, dialysis fluid compositions and amounts, dialysis temperatures, sample amounts, and dialysis times. The best results were obtained by dialysis of 7.50 g sample in a cellulose dialysis sack, using two 3 L portions of 0.015 M sodium phosphate buffer (pH 7.0) as the dialysis fluid at 4 degrees C for 22 h. As in previous methods, catalase activity was determined on the basis of the rate of disappearance of the substrate, H202, with the H202 determined spectrophotometrically at 400 nm in an assay system containing o-dianisidine and peroxidase. Trials indicated that the best solvent for the o-dianisidine was 0.2 M sodium phosphate buffer, pH 6.1; the best starting H202 concentration was 3 mM; the best HCl concentration for stopping the reaction was 6 N; and the best sample volume for catalase measurement was 7.0 mL. Precision values (relative standard deviations for analyses of 10 subsamples of each of 3 samples) were high, ranging from 0.48% for samples with high catalase activity to 1.98% for samples with low catalase activity.