Ángela Casado

Overexpression of copper-zinc superoxide dismutase in trisomy 21

Downs syndrome (DS), the most frequent of congenital birth defects, results from the trisomy of chromosome 21 in all cells of affected patients. This disease is characterized by developmental anomalies, mental retardation and features of rapid aging, particularly in the brain, where the occurrence of Alzheimers disease is observed in trisomy 21 patients over the age of 35. Copper-zinc superoxide dismutase (CuZnSOD) is one of the proteins encoded by chromosome 21 (21q22.1). As a consequence of gene dosage excess, CuZnSOD activity is increased by 50% in all DS tissues. This work reports the SOD activity of a population of DS patients with complete trisomy 21, partial trisomy 21, translocations and mosaicism, in order to confirm the gene dosage effect of SOD on the clinical features of DS, and to help to establish which is the critical region of chromosome 21 in DS. CuZnSOD was measured in red blood cells using the Minami and Yoshikawa method. In the population with complete trisomy 21, SOD activity was increased by 42%; in the population with partial trisomy 21, translocations and mosaicism, SOD activity was normal. In the population diagnosed as DS, but not karyotyped, SOD activity was increased by 28%. No differences between sexes or among ages were found. We conclude that the 21q22.1 segment is not the critical region responsible for DS, as we have found normal SOD activity in patients with the clinical features of DS.

Evaluation of the copper(II) reduction assay using bathocuproinedisulfonic acid disodium salt for the total antioxidant capacity assessment: The CUPRAC–BCS assay

There is heightened interest in determining antioxidant status of individuals in experimental and clinical studies investigating progression of diseases or diverse aspects of oxidative stress, among others. The aim of this study was to evaluate the copper(II) reduction assay with bathocuproinedisulfonic acid disodium salt as chelating agent (the CUPRAC-BCS assay) for the total antioxidant capacity (TAC) assessment in human plasma and urine. Samples from 20 individuals were determined with four spectrophotometric assays-CUPRAC-BCS, ferric reducing ability of plasma (FRAP), trolox equivalent antioxidant capacity (TEAC), and 1,1-diphenyl-2-picrylhydrazyl assay (DPPH)-to compare these methods. CUPRAC-BCS was significantly correlated with FRAP and TEAC for plasma and urine samples (r>0.5, P<0.05 for all) and with DPPH for urine samples (r=0.925, P<0.001) but not with DPPH for plasma samples (r=0.366, P=0.112). However, the four methods do not agree given that lines of equality and regression were not matched up. The imprecision of the method is less than 6%, the detection limit is 41.8 micromol trolox equivalents/L, it is linear up to 2 mM trolox, and ethylenediaminetetraacetic acid dihydrate disodium salt (EDTA) binds to Cu(II), avoiding the formation of Cu(I)-BCS complex. This study shows that CUPRAC-BCS is a simple, fast, inexpensive, and suitable method for TAC assessment in human urine and heparinized plasma samples.

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 = 103.117e0.0021.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.

Human aging brain disorders: role of antioxidant enzymes.

In order to investigate the role of two free radical detoxificant enzymes in patients with aging brain disorders, superoxide dismutase (SOD) and catalase (CAT) activities have been measured in blood from male and female human patients of different ages with several types of aging brain disorders. When compared with activities in the normal population, we have detected: 1) SOD and CAT activities are decreased in patients with Parkinson disease. 2) SOD activity seems to be normal and CAT activity is decreased in patients with dementia. 3) In the patients with stroke, SOD activity is normal, while CAT activity is decreased. SOD activity was measured in red blood cells using the Minami and Yoshikawa method. CAT activity was measured in hemolysates by the method of Aebi. We can conclude that SOD and CAT activities in patients with Parkinson disease are decreased.

Urinary biomarkers of oxidative/nitrosative stress in healthy smokers

Objective: To evaluate the effect of cigarette smoking on oxidative and nitrosative stress, we assessed urinary levels of 8-hydroxy-2′-deoxyguanosine (8-OHdG), isoprostane 15-F2t-IsoP, thiobarbituric acid-reacting substances (TBARS), advanced glycation end-products (AGEs), dityrosine (diTyr), hydrogen peroxide, total nitrite and nitrate and trolox equivalent antioxidant capacity (TEAC) in healthy smokers. Methods: Fluorimetric and spectrophotometric assays were performed in urine samples of 33 healthy smokers and 58 age-matched controls. Results: Levels of 8-OHdG, 15-F2t-IsoP and AGES were found significantly higher in smokers than in controls (10.7 ng/mg Cr vs. 8.3 ng/mg Cr, 1.41 ng/mg Cr vs. 1.01 ng/mg Cr and 189 AFU/mg Cr vs. 143 AFU/mg Cr, respectively; P < 0.05 for all). Positive correlations were found between age and levels of AGEs and diTyr in smokers (r = 0.380, P < 0.035 and r = 0.418, P < 0.019, respectively) and also between age and AGEs, diTyr and TEAC in controls (r = 0.474, P < 0.001, r = 0.463, P < 0.001 and r = 0.576, P < 0.001, respectively), being this correlation negative for 8-OHdG in controls (r = −0.295, P = 0.041). Positive correlation between the number of cigarettes smoked per day and AGEs was also found (r = 0.355, P = 0.044). Conclusion: Urinary 8-OHdG, 15-F2t-IsoP and AGEs may represent a non-invasive quantitative index of oxidant stress in healthy smokers, being AGEs a possible indicator of tobacco toxin exposure. The increased oxidative stress in healthy smokers observed may be generated because of an excessive production of reactive oxygen species and not by exhaustion of antioxidant defenses.

Antioxidant Enzyme Levels in Red Blood Cells from Cataract Patients

Background: It seems very likely that oxidative mechanisms play a major role in aetiology and pathogenesis of senile cataract. In particular, lens proteins are subject to extensive oxidative modifications. Objective: The purpose of this work was to analyze the activities of the protective enzymes superoxide dismutase (SOD) and catalase (CAT) in patients of both sexes affected by cataract. Methods: The SOD activity was measured in red blood cells using the Minami and Yoshikawa method, and the CAT activity was measured in haemolysates by the method of Aebi. The results were compared with those obtained in a group of healthy subjects of both sexes and matched ages. Results: The SOD activity shows a significant increase when compared with controls, whereas the CAT activity was not modified. Conclusion: The balance of the anti-oxidants in red blood cells from cataract patients is altered.

Superoxide dismutase and catalase blood levels in patients with malignant diseases

Superoxide dismutase (SOD) and catalase (CAT) activities have been measured in blood from male and female patients of different ages with several types of cancer, in order to examine the relationship among cancer and the two free radical detoxificant enzymes. SOD activity in patients with cancer was found not to be significantly different from the SOD activity observed in the normal population. CAT activity was lower in patients with cancer, especially in lymphomas, when compared with CAT activity in the normal population.

Relationship between oxidative and occupational stress and aging in nurses of an intensive care unit

Stressful conditions lead to formation of excessive reactive oxygen species (ROS) and cause oxidative stress and aging. The aim of this study was to determine superoxide dismutase (SOD) and catalase (CAT) activity, and malondialdehyde (MDA) levels in nurses of a hospital intensive care unit according to demographic and occupational parameters, and to analyse the relationship with aging. Thirty-two nurses working in an intensive care unit and 35 aged-matched healthy individuals of both sexes as a control group were surveyed. No significant variations with respect to sex were detected in SOD, CAT, MDA and burnout levels. MDA levels increased with age in both the control group and the nurses, and we observed significant differences in MDA levels between the control group and nurses for all age groups. Significant variations in MDA levels were detected between single (286.12 ± 8.41) and married (318.82 ± 6.02), people, between those who frequently practice some kind of sport (281.41 ± 7.32) and those who never participate in sport (298.24 ± 8.11) ,and between those who frequently eat fruit and greens (289.75 ± 8.41) and those who never eat them (315.12 ± 7.21). Significant differences were detected between smokers and nonsmokers in SOD, CAT and MDA, but not for alcohol, coffee, tea or cola consumption. Higher SOD activity and MDA levels were detected in nurses on evening and night shifts (P < 0.01); these nurses also scored significantly higher on burnout subscales. These results suggest that: (1) occupational stress increases oxidative stress levels as a response to elevated ROS generation; (2) occupational stress increases MDA levels as a response to an elevation in free radical generation and can lead to aging; (3) working evening and night shifts increases oxidative and burnout levels. It is evident that preventive changes in job conditions and lifestyle are necessary to improve the quality of life of nurses who work in intensive care units.

Urinary uric acid and antioxidant capacity in children and adults with Down syndrome

OBJECTIVES To evaluate the urinary levels of uric acid (UA) and total antioxidant capacity (TAC) with and without UA relative contribution (TAC(-UA)) in children and adults with Down syndrome (DS) and to prove the clinical use of TAC. DESIGN AND METHODS Urine samples were obtained from 32 individuals with DS and 29 controls. Two age groups were established (children and adults). Spectrophotometric methods were used for biochemical determinations. RESULTS Children with DS had significantly higher UA/Cr and TAC/Cr levels than controls, whereas levels of TAC(-UA)/Cr were lower in adults with DS than in controls (P<0.05 for all). In DS, levels of UA/Cr, TAC/Cr and TAC(-UA)/Cr were higher in children than in adults (P<0.05 for all). Positive correlations between UA/Cr and TAC/Cr were found for all groups studied. Negative correlations with age were found for UA/Cr and TAC/Cr in children of both groups. CONCLUSIONS Our results proved that TAC is decreased in adults with DS. Besides, TAC(-UA) seems to provide more reliable information about the antioxidant status, at least in DS.

Lipid peroxidation in Down syndrome caused by regular trisomy 21, trisomy 21 by Robertsonian translocation and mosaic trisomy 21

Abstract Background: It has been suggested that an increase in oxidative stress in individuals with Down syndrome (DS) may cause adverse effects in the cell membranes through the oxidation of polyunsatured fatty acids. Methods: We examined erythrocyte malondialdehyde (MDA) levels in 100 individuals of both sexes (34 males and 66 females) with DS, aged from newborn to 29 years. The cytogenetic analysis revealed 90 individuals with regular trisomy 21, four individuals with trisomy 21 by Robertsonian (Rb) translocation, and six individuals with mosaic trisomy 21. DS individuals were divided into six age groups. The control group consisted of 100 healthy individuals of both sexes (40 males and 60 females) who were age-matched with DS subjects. Results: No significant differences were found in erythrocyte MDA levels between the sexes in any of the age groups for the DS group and the control group. We confirmed significantly higher erythrocyte levels of MDA in individuals with DS compared to the control group. A significant difference was observed in erythrocyte MDA levels between DS individuals with trisomy and controls for all age groups, and in individuals with DS due to Rb translocation trisomy. However, in DS individuals with mosaicism, MDA levels depended on the percentage of diploid and trisomy cells. Conclusions: Our results confirm an increase in lipid peroxidation in patients with DS. Clin Chem Lab Med 2007;45:59–62.