Encarnación López-Fernández

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.

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.

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.

Biomarkers of age effect on renal function in Down syndrome

Objective: To assess differences in kidney function between Down syndrome (DS) individuals and a control group related to aging. Methods: Creatinine (Cr) and specific gravity (SG) were assessed by spectrophotometric and refractometric assays in urine samples of 103 individuals with DS and 82 age-matched controls. Results: Significantly lower levels of Cr and SG were found in DS after puberty. Significant correlations were found between SG and age as well as between Cr and SG in DS and controls (p ≤ 0.05). Conclusions: Premature aging in kidneys of DS patients could lead to an impaired renal function.

Hematologic and biochemical observations in Gazella dama, G. dorcas and G. cuvieri

1. Blood samples obtained from 114 animals of three species of the genus Gazella (Gazella dama, Gazella dorcas and Gazella cuvieri) were analyzed from hematology (osmotic fragility, red blood cells morphology and hemoglobin electrophoresis) and biochemical values (glucose-6-phosphate dehydrogenase, pyruvate kinase and glutathione reductase deficiencies and superoxide dismutase activity). 2. Standard methods were used. Hemoglobin polymorphism was found. 3. There was no abnormality in the osmotic fragility and red blood cells morphology. 4. The biochemical results are compared with information from the literature and with the normal human range.