Lipid peroxidation, antioxidant enzymes and glutathione levels in human erythrocytes exposed to colloidal iron hydroxide in vitro

The free form of the iron ion is one of the strongest oxidizing agents in the cellular environment. The effect of iron at different concentrations (0, 1, 5, 10, 50, and 100 µM Fe3+) on the normal human red blood cell (RBC) antioxidant system was evaluated in vitro by measuring total (GSH) and oxidized (GSSG) glutathione levels, and superoxide dismutase (SOD), catalase, glutathione peroxidase (GSH-Px) and reductase (GSH-Rd) activities. Membrane lipid peroxidation was assessed by measuring thiobarbituric acid reactive substance (TBARS). The RBC were incubated with colloidal iron hydroxide and phosphate-buffered saline, pH 7.45, at 37oC, for 60 min. For each assay, the results for the control group were: a) GSH = 3.52 + ou - 0.27 µM/g Hb; b) GSSG = 0.17 + ou - 0.03 µM/g Hb; c) GSH-Px = 19.60 + ou - 1.96 IU/g Hb; d) GSH-Rd = 3.13 + ou - 0.17 IU/g Hb; e) catalase = 394.9 + ou - 22.8 IU/g Hb; f) SOD = 5981 + ou - 375 IU/g Hb. The addition of 1 to 100 µM Fe3+ had no effect on the parameters analyzed. No change in TBARS levels was detected at any of the iron concentrations studied. Oxidative stress, measured by GSH kinetics over time, occurs when the RBC are incubated with colloidal iron hydroxide at concentrations higher than 10 µM of Fe3+. Overall, these results show that the intact human RBC is prone to oxidative stress when exposed to Fe3+ and that the RBC has a potent antioxidant system that can minimize the potential damage caused by acute exposure to a colloidal iron hydroxide in vitro.

The evaluation of clotting time in bovine thrombin, reptilase©, and thrombin-like fraction of Crotalus durissus terrificus venom using bovine, equine, ovine, bubaline and human cryoprecipitates

The objective of this study was to evaluate the effects of the thrombin-like fraction of Crotalus durissus terrificus venom, Reptilase©, and bovine thrombin of fibrinogen polls on bovine, equine, ovine, bubaline and human cryoprecipitates. The authors also made a comparative study between animal and human cryoprecipitates to see if there was any possibility of future use in medicine. Fibrinogen levels in cryoprecipitate were studied using 48 blood samples obtained as follows: 12 samples from humans, 9 from bovine, 10 from equine, 10 from ovine and 7 from bubaline. The results obtained showed average levels of 375.50 mg per cent for humans, 218.33 mg per cent for bovine, 240.80 mg per cent for equine, 267.70 mg per cent for ovine and 664.00 mg per cent for bubaline. Upon the formation of pools of human and animals fibrinogens, the following results were obtained: 435 mg per cent for humans, 444 mg per cent for bovine, 337 mg per cent por equine, 390 mg per cent for ovine and 530 mg per cent for bubaline. Statistical analysis (using the analysis of variance for entirely randomized experiment for the calculation of F statistics) demonstrated that the bubaline fibrinogen level was higher than that of human, and both were higher than those of ovine, equine, and bovine. Clotting times were determined using different dilutions of bovine thrombin, thrombin-like fraction of Crotalus durissus terrificus venom, and Reptilase©. Comparing these clotting times, results for human and bovine were found to be very similar, whereas using equine, ovine and bubaline the results above a dilution of 1:3 were markedly different. The results obtained permitted the following conclusions to be drawn show that: 1) bovine thrombin presented better interactivity with fibrinogen extracted both from human and bovine cryoprecipitates; 2) there was similar behavior when bovine thrombin was substituted for Reptilase© and for the thrombin-like fraction of Crotalus durissus terrificus venom; 3) cryoprecipitate from bovine can, in special circumstances, substitute human cryoprecipitate in medical practice; 4) human and bovine cryoprecipitates can be used with both Reptilase© and Crotalus durissus terrificus fractions using a dilution up to 1:5; 5) the use of bovine cryoprecipitate can be recomended using either bovine thrombin, Reptilase©, or thrombin-like fraction of Crotalus durissus terrificus venom.

Influence of diabetes mellitus on the glutathione redox system of human red blood cells

Several components of the erythrocyte-dependent glutathione redox system (reduced glutathione, GSH; oxidized glutathione, GSSG; glutathione peroxidase, GSH-Px; glutathione reductase, GSH-Red) were determined in patients with types I and II diabetes mellitus (DM). All groups studied were male subjects: G1, 200 young healthy individuals (aged 23.7 ñ 4.2 years); G2, 15 young insulin-treated type I DM patients; G3, 20 older older insulin-treated type II DM patiens; G4, 21 older oral hypoglycemic agent-treated type II DM patients; G5, 28 aged healthy individuals (aged 68.9 ñ 11.5 years). There were no differences between G1 and G3 or G4 regarding erythrocyte GSH, GSSG, and GSH-Red (without FAD) levels. GSH-Px activity was significantly lower in G2 when compared to G1 (15.2 ñ 4.9 vs 20.6 ñ 6.6 IU/g Hb). The GSH-Red and GSH-Px activities and GSH levels were significantly higher in G3 (4.6 ñ 1.7 IU/g Hb, 20.2 ñ 8.7 IU/g Hb and 3.5 ñ 1.3 uM/g Hb) and G4 (5.0 ñ 2.2 IU/g Hb, 16.9 ñ 6.1 IU/g Hb and 5.0 ñ 2.3 uM/g Hb) when compared to G5 (3.4 ñ 0.9 IU/g Hb, 12.0 ñ 3.6 IU/g Hb and 2.3 ñ 0.9 uM/g Hb). The findings suggest that treatment of DM can stimulate the redox activity of red blood cells in aged subjects

Age-related changes of glutathione content, glutathione reductase and glutathione peroxidase activity of human erythrocytes

In order to investigate the effect of aging on the erythrocyte glutathione system, total glutathione (GSH), glutathione reductase (GSH-red) and glutathione peroxidase (GSH-px) levels were measured in erythrocyte from 33 young (mean age=30.5ñ9.7 years) and 28 aged (mean age+68.9ñ11.4 years) healthy individuals. GSH was 3.5ñ1.8 *M/g Hb for the young group, a value significantly greater (P<0.01) than 2.3ñ0.9 *M/g Hb found for the aged group. Similary, GSH-red activity, 5.5ñ1.8 IU/g Hb, was higher (P,0.05) for the young group than 3.4ñ0.9 IU/g Hb found for the aged group. The GSH-px activity levels for the young group, 21.1ñ5.9 IU/g Hb, were significantly greater (P<0.01) than 12.0ñ3.3 IU/g Hb for the age group. The lower activity detected in the aged group for all of these parameters of the glutathione redox system was not related to low levels of hematocrit or hemoglobin. There was no statistical difference in the activation coefficient (AC) of reductase (+FAD/-FAD) between groups, which seems to indicate that the lower activity of glutathione reductase observed in the aged group was not due to riboflavin deficiency. Additional information is required to determine the mechanisms controlling the glutathione redox system and its role in the aging process