Damage to red blood cells by halocompounds

Hemoglobin and red blood cells catalyze atom transfer radical polymerization

Hemoglobin (Hb) is a promiscuous protein that not only transports oxygen, but also catalyzes several biotransformations. A novel in vitro catalytic activity of Hb is described. Bovine Hb and human erythrocytes were found to display ATRPase activity, i.e., they catalyzed the polymerization of vinyl monomers under conditions typical for atom transfer radical polymerization (ATRP). N-isopropylacrylamide (NIPAAm), poly(ethylene glycol) methyl ether acrylate (PEGA), and poly(ethylene glycol) methyl ether methacrylate (PEGMA) were polymerized using organobromine initiators and the reducing agent ascorbic acid in acidic aqueous solution. In order to avoid chain transfer from polymer radicals to Hb's cysteine residues, the accessible cysteines were blocked by a reaction with a maleimide. The formation of polymers with bromine chain ends, relatively low polydispersity indices (PDI), first order kinetics and an increase in the molecular weight of poly(PEGA) and poly(PEGMA) upon conversion indicate that control of the polymerization by Hb occurred via reversible atom transfer between the protein and the growing polymer chain. For poly(PEGA) and poly(PEGMA), the reactions proceeded with a good to moderate degree of control. Sodium dodecyl sulfate (SDS) gel electrophoresis, circular dichroism spectroscopy, and time-resolved ultraviolet-visible (UV-vis) spectroscopy revealed that the protein was stable during polymerization, and only underwent minor conformational changes. As Hb and erythrocytes are readily available, environmentally friendly, and nontoxic, their ATRPase activity is a useful tool for synthetic polymer chemistry. Moreover, this novel activity enhances the understanding of Hb's redox chemistry in the presence of organobromine compounds.

In vivo effects of non-steroidal antiinflammatory drugs on oxidative stress-related parameters of human erythrocytes

In this study, we evaluated the effects of commonly used non-steroidal anti-inflammatory drugs (NSAIDs) on oxidative stress and anti-oxidant system. Sixteen healthy volunteers and 35 patients diagnosed as one of musculoskeletal disorders were included in the study. Patients were treated with one of the three NSAIDs (i.e. naproxen, tiaprofenic acid, acemetacin) or paracetamol for 15 days. Erythrocyte glutathione S-transferase, erythrocyte and plasma glutathione peroxidase, and erythrocyte catalase (CAT) activities and plasma malondialdehyde level as lipid peroxidation index were detected in the blood samples of the patients, at the beginning of the study (0 week), after treatment for 15 days (2nd week), and at the end of 1 week-washout period (3rd week). The most affected enzyme by NSAIDs was erythrocyte catalase, which tended to increase at the end of 2 weeks treatment, and decrease at the end of 1 week-washout period. In the groups treated with acemetacin, naproxen and tiaprofenic acid, plasma malondialdehyde levels were decreased at some extent, but at the end of washout period a rebound increase was observed in acemetacin group. Our results suggest that NSAIDs have different influences on oxidative stress and anti-oxidant system related parameters. These effects seem to be related with the mechanisms of some of the adverse effects, which are not well understood yet. Further studies with larger groups are needed to illuminate the relationship between adverse effects of NSAIDs and the effects of these drugs on anti-oxidant system, and to clarify their mechanisms of therapeutic action, as well.

Potentiation of oxidative damage to rat red blood cells by the concurrent presence of t-butyl hydroperoxide and bromotrichloromethane

Recently potentiation of oxidative damage in rat red blood cells (rRBC) incubated with t-butylhydroperoxide (BHP) in combination with bromotrichloromethane (BrCCI3) was demonstrated. The mechanism by which this combination (BrCCI3/BHP) potentiates the oxidative damage to rRBC was investigated in this study. When rRBC were incubated with 0.1 mM BHP, 0.5 mM BrCCI3, or the two combined, BrCCI3/BHP-potentiated lipid peroxidation and hemolysis were further enhanced under anaerobic conditions. However, the potentiation of lipid peroxidation was abolished by heating or trypsin digestion of rRBC. Electron spin resonance (ESR) studies demonstrated an increase of alkoyl radical induced by BrCCI3/BHP in rRBC, and this increase was abolished by heating or predigestion of hemolysates with trypsin. The inhibition of lipid peroxidation by diphenylamine (which reacts with alkoxyl radicals but not peroxyl radicals) suggests an important role of alkoxyl radicals. Overall, the present findings demonstrate that the increase in radical-related oxidative damage, possibly mediated by proteinlike materials, may be at least partially responsible for the potentiation of damage to rRBC induced by BrCCI3/BHP, and perhaps by BrCCI3. Although the in vivo significance of these results remains to be investigated, it seems likely that halocarbon toxicity may be amplified by elevated levels of lipid peroxide in blood.

Influence of lindane and paraquat on oxidative stress-related parameters of erythrocytes in vitro

1. The influence of lindane and paraquat on oxidative stress-related parameters of the red blood cell was studied in vitro. 2. Lindane addition did not modify either the t-butyl hydroperoxide-induced oxygen uptake of the erythrocytes and the induction time preceding it, or the activity of catalase, superoxide dismutase, glutathione peroxidase and glucose 6-phosphate dehydrogenase, in conditions of comparable levels of haemoglobin and methaemoglobin. 3. Red blood cells exposed to paraquat exhibited a concentration-dependent decrease in the t-butyl hydroperoxide-induced oxygen consumption and increments in either the induction period or in the activity of catalase and glucose 6-phosphate dehydrogenase, with no changes in superoxide dismutase activity and a small decrement in that of glutathione peroxidase. 4. These data indicate that lindane does not interfere with the oxidant status of the erythrocyte, while paraquat addition leads to an increment in the anti-oxidant capacity of the red blood cell.

Acute lindane intoxication: a study on lindane tissue concentration and oxidative stress-related parameters in liver and erythrocytes

Treatment of rats with daily doses of 20 mg of lindane/kg for 3 consecutive days led to the accumulation of the insecticide in several tissues, including erythrocytes and liver. Lindane did not alter the hematocrit and hemoglobin concentration but reduced methemoglobin levels by 17%. Red blood cells from controls and lindane-treated rats, exposed to t-butyl hydroperoxide, exhibited comparable rates of oxygen uptake and visible chemiluminescence, whereas the induction period that precedes oxygen uptake was significantly enhanced in the latter group. Lindane treatment did not modify the activity of erythrocyte glutathione peroxidase, glucose-6-phosphate dehydrogenase, catalase, and methemoglobin reductase, being the total content of glutathione and superoxide dismutase activity significantly increased. The liver from lindane-treated rats showed an enhanced microsomal pro-oxidant activity, evidenced by higher cytochrome P450 content and NADPH-cytochrome c reductase and NADPH oxidase activities. The higher enzyme activities led to an increased superoxide anion generation (adrenochrome formation) and lipid peroxidation (measured either by the production of thiobarbituric acid reactants and spontaneous visible chemiluminescence). Concomitantly, liver glutathione content and the activity of glutathione peroxidase-glutathione reductase couple were augmented by lindane treatment, without any change in superoxide dismutase activity, together with a reduction in that of catalase. Results suggest that lindane does not alter the prooxidant/antioxidant status of the erythrocyte in conditions of a significant cellular accumulation of the insecticide, which might exert direct action on enzymatic systems leading to enhanced superoxide dismutase activity and glutathione content.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of short-term lindane administration on parameters related to oxidative stress in rat liver and erythrocytes

Parameters related to oxidative stress in rat liver and erythrocytes were studied after short-term administration (60 and 90 days) of 1000 ppm of lindane in the diet. Lindane induced an oxidative stress condition in the liver, which is related to an enhancement in microsomal NADPH-cytochrome c reductase and NADPH oxidase activities, superoxide radical formation and cytochrome P450 content, produced independently of the time of treatment. Also, decreased activities of glutathione peroxidase and catalase were concomitantly observed. Although these changes were paralleled by an increase in lipid peroxidation indices, such as production of thiobarbituric acid reactants and spontaneous chemiluminescence, no evidence of liver injury was obtained. Lindane treatment did not exert quantitatively important changes in the pro-oxidant/anti-oxidant status of the erythrocyte, with reduction in the red blood cell mass possibly reflecting actions of the insecticide on the erythropoietic process.

Formation of methemoglobin by 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone, MX, in rat erythrocytes in vitro

Oxidative effects of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), the principal bacterial mutagen in chlorinated drinking water were studied in rat erythrocytes. Upon incubation of rat blood with 14C-labelled MX (2 micrograms/ml), 42% of the radioactivity was found in plasma, 26% in erythrocyte cell membranes and 32% bound in hemoglobin. Although it was bound to hemoglobin, MX (1 mM) did not immediately affect the oxygen binding capacity of hemoglobin. MX (0.5 to 5 mM) decreased the portion of oxyhemoglobin and increased that of methemoglobin in erythrocytes suspended in buffer in a time- and concentration-dependent fashion. In the same concentration range MX did not stimulate proteolysis nor did it cause hemolysis in erythrocytes. The results indicate that MX binds to hemoglobin and stimulates oxidation of hemoglobin in erythrocytes but MX does not cause overt oxidative damage to erythrocytes.