Trophic enteral nutrition increases hepatic glutathione and protects against peroxidative damage after exposure to endotoxin

BACKGROUND

During total parenteral nutrition (TPN), hepatic concentration of the important intracellular antioxidant glutathione (GSH) is decreased. This study sought to determine whether enteral trophic (small quantity) feeding of GSH precursors would increase hepatic GSH levels during TPN and result in decreased peroxidative injury after endotoxin exposure.

METHODS

Sprague-Dawley rats received full TPN for 7 days with postpyloric infusions of either (1) amino acid GSH precursors (cysteine, 60 mg/d; glycine, 86 mg/d; glutamate, 31 mg/d; F1); (2) iso-nitrogenous alanine (132 mg/d; F2); or (3) normal saline (SA). Hepatic GSH concentration was measured by gas chromatography/mass spectrometry. In a parallel study, animals were given TPN and either F1 or SA for 7 days, and endotoxin was administered intravenously before death. Hepatic lipid peroxidation and histology were assessed.

RESULTS

Hepatic GSH concentration measured 11.7 +/- 0.6 micromol/g in F1. This was significantly higher (P <.001) than in F2 (7.0 +/- 0.8 micromol/g) or SA (5.0 +/- 0.4 micromol/g). F2 and SA were not significantly different. Hepatic malondialdehyde concentration after exposure to endotoxin was significantly higher in SA (10.36 micromol/g +/- 0.65) than in F1 (7.38 micromol/g +/- 0.77; P <.01). All SA animals had histologic evidence of hepatic necrosis, whereas none of the F1 group showed these changes.

CONCLUSIONS

Targeted trophic feeding of GSH amino acid precursors during parenteral nutrition markedly increased hepatic GSH concentration. This was associated with decreased lipid peroxidation and enhanced hepatocellular protection after endotoxin challenge. Thus, targeted trophic feedings may aid in the prevention of TPN-related liver disease.

Effect of thiazolidinediones and metformin on LDL oxidation and aortic endothelium relaxation in diabetic GK rats

In this study, using GK diabetic rats, we compared the effects of three insulin sensitizers on lipid oxidation and the aortic relaxation response. Eight-week-old rats were treated for 4 wk with either troglitazone or pioglitazone, both of which are thiazolidinediones, or with metformin. Despite the fact that only troglitazone has a similarity in structure to alpha-tocopherol, a potent antioxidant, the level of thiobarbituric acid-reactive substance was lower, and the lag time of the conjugated dienes was longer, in the blood samples from the rats in both troglitazone- and pioglitazone-treated groups. In contrast, another insulin sensitizer, metformin, failed to inhibit the oxidation of blood samples. The aortic vasorelaxation response was increased in both troglitazone- and metformin-treated groups compared with the untreated group. These findings suggest that thiazolidinediones have a beneficial effect on lipid oxidation irrespective of the drug's structural similarity to alpha-tocopherol. It is also suggested that the thiazolidinediones and metformin improve vascular function in diabetes. These effects may play a role in the prevention of atherosclerosis in diabetic patients.

Tea can protect against aberrant crypt foci formation during azoxymethane induced rat colon carcinogenesis

Tea shows many health promoting activities including chemopreventive action during carcinogenesis due to the presence of antioxidative polyphenolic constituents. The present experiment evaluated the anticarcinogenic role of black tea infusion on azoxymethane induced colonic preneoplastic lesions, the aberrant crypt foci in Sprague-Dawley rats. Rats were injected with azoxymethane (15 mg/kg b.w.) and received oral administration of 1% and 2% (w/v) tea infusions from first day of carcinogen application. This treatment was continued for twelve weeks and assessed for aberrant crypt foci and compared with untreated carcinogen control group. Levels of lipid peroxidation were determined in liver as well as in colon tissue. During initiation phase of carcinogenesis, glutathione-S-transferase (GST) and glutathione peroxidase (GPx) activities were also evaluated. Significant reduction in the number of aberrant crypt foci and levels of lipid peroxidation among the tea-treated groups were observed. Induction of GST and GPx activities was noted during the initiation phase of carcinogenesis. Results of the present study indicate that the protective effect of black tea infusions may be due to an outcome of antioxidative influence of tea components on azoxymethane induced carcinogenesis.

[Studies on 2-hydroxyestradiol 17-sulfate derived from fetoplacental unit: the antioxidant as a potential defense substance against preeclampsia]

The antioxidant 2-hydroxyestradiol 17-sulfate (2-OH-E2-17-S) was found to be present in the placenta and to prevent the onset of preeclampsia. From experiments using rats, 2-OH-E2-17-S was confirmed to be a highly functional compound with stronger antioxidant activity than alpha-tocopherol and to sustain its antioxidant activity. 2-OH-E2-17-S was confirmed to be produced in the placenta from its precursor, estradiol 17-sulfate (E2-17-S), which is derived from fetal testosterone sulfate (TS). Since the fetal adrenal gland has been shown to convert testosterone (T) into TS, the following metabolic pathway may exist during pregnancy: T-->TS-->E2-17-S-->2-OH-E2-17-S. This fetoplacental pathway may contribute to the maintenance of healthy pregnancy. Details and the experimental outline of these discoveries are reported in this review.

Effect of long-term hypokinesia on monoamine system and antioxidant status of the brain

Long-term hypokinesia (30 days) was accompanied by activation of the serotoninergic and dopaminergic systems. Exhaustion of the antioxidant system was observed on days 10-30 of immobilization.

Fibrates and their newly synthesized glycinate or glycinate-methylester derivatives: comparison of the interactions with liver cytochrome P450 dependent monooxygenase- and oxidase-functions in vitro

Different fibrates (bezafibrate, ciprofibrate, clofibrate, fenofibrate, gemfibrozil) were investigated in comparison with their newly synthesized glycinate and glycinate-methylester derivatives. Interactions with the cytochrome P450 (CYP) system were studied by assessing binding to CYP and effects on CYP mediated monooxygenase functions in rat liver 9000 g supernatants, as measured by six model reactions for different CYP isoforms (ethoxyresorufin O-deethylation, ethoxycoumarin O-deethylation, pentoxyresorufin O-depentylation, p-nitrophenol-hydroxylation, ethylmorphine N-demethylation, lauric acid 11- or 12-hydroxylation). Possible prooxidant or antioxidant properties were investigated by the stimulated lipid peroxidation, hydrogen peroxide production, and lucigenin and luminol amplified chemiluminescence using rat liver microsomes. Additionally, the influence on luminol amplified rat whole blood chemiluminescence was examined. All substances tested displayed binding to CYP. Effects on the monooxygenase model reactions were in general more distinct with the glycinates than with the parent compounds and most pronounced with the glycinate-methylester derivatives. The slightest effects on all model reactions were seen with clofibrate and its derivatives. On the whole, low antioxidative rather than prooxidative effects were observed. In general and with most model reactions, the antioxidative capacity of the glycinate and glycinate-methylester derivatives slightly exceeded that of the respective parent compounds. Summarizing the results it can be concluded that with respect to possible interactions with the CYP system in vivo and thus with the biotransformation of other concomitantly administered compounds no advantages of the glycinate or glycinate methylester derivatives over their parent fibrates are to be expected. Only the antioxidative capacity of the derivatives was somewhat higher than that of the parent substances, though most probably only of minor therapeutical relevance.

[Drug- and toxin-induced hepatotoxicity]

The liver is essential for metabolism of drugs and exogenous toxins. Therefore, liver toxicity due to natural, domestic and industrial toxins or drugs is common but rarely recognised. Although thorough epidemiological data are missing, the number of cases with drug-induced liver toxicity is increasing, parallel to the growing number of drugs. Adverse hepatic reactions may present as acute or chronic liver damage. Independent from the cause and mechanism of liver damage, the clinical presentation may be either cytolytic or cholestatic. In addition, liver damage may be accompanied by a systemic hypersensitivity reaction against the applied agent. Drug- or toxin-induced liver damage includes vascular damage, induction of liver tumours and development of liver cirrhosis. The prerequisite for specialised treatment of drug-induced adverse hepatic reactions is establishing the diagnosis which is obtained by a thorough medical history taken by an experienced physician with a special emphasis on drug or toxin exposure. The diagnosis may be confirmed by additional diagnostic measures (e. g. liver biopsy) or the clinical course after exposure to the causing agent has been stopped. Only in a minority of cases a definite treatment may be available. Therefore, the main aim is to prevent chronic liver damage through early and correct diagnosis. Due to the extensive variety of possibly liver toxic drugs and chemical agents this aspect is a major challenge to physicians.

Enhancement of cold tolerance and inhibition of lipid peroxidation by citrus dehydrin in transgenic tobacco

Citrus ( Citrus unshiu Marcov.) dehydrin in response to chilling stress was overexpressed in tobacco ( Nicotiana tabacum L.), and the cold stress tolerance of transgenics at low temperature was analyzed. The freezing at -4 degrees C for 3 h of 24 independent lines indicated that a phenotype expressing citrus dehydrin showed less electrolyte leakage than the control. Dehydrin protein content was correlated with freezing tolerance in transgenics. Dehydrin-expressing tobacco exhibited earlier germination and better seedling growth than the control at 15 degrees C. Cell fractionation experiments suggested that the protein was predominantly expressed in mitochondria and the soluble fraction. Malondialdehyde production enhanced by chilling stress was lower in tobacco plants expressing citrus dehydrin than in control phenotypes. Dehydrin protein, purified from Escherichia coli expressing citrus dehydrin cDNA, prevented peroxidation of soybean ( Glycine max L.) liposomes in vitro. The inhibitory activity of dehydrin against liposome oxidation was stronger than that of albumin, glutathione, proline, glycine betaine, and sucrose. These results suggest that dehydrin facilitates plant cold acclimation by acting as a radical-scavenging protein to protect membrane systems under cold stress.

Evaluation of the effect of lipoic acid administered along with gentamicin in rats rendered bacteremic

Gentamicin is an aminoglycosidic antibiotic widely used in the treatment of many gram-negative bacterial infections. The present study was designed to investigate the extent of nephrotoxicity and the degree of protection afforded by lipoic acid under E. coli infected conditions and to note its effect on the antimicrobial activity of gentamicin. The study was carried out with adult male albino rats of Wistar strain. Group I animals served as controls. Group II animals were injected intraperitoneally for 2 successive days with 0.2 ml inoculum containing 10(10)) colony forming units of E. coli. Group III animals were injected E. coli as those in group II, in addition gentamicin 100 mg kg(-1) was administered intraperitoneally for 10 successive days. Group IV animals received intraperitoneal injections of E. coli as above plus gentamicin and also received lipoic acid (25 mg kg(-1)) for 10 days by oral gavage. Rats subjected to E. coli administration showed a decline in the thiol content of the cell accompanied by high malondialdehyde levels along with lowered activities of catalase, superoxide dismutase and glutathione peroxidase with an added effect observed when gentamicin was administered along with it. The extent of nephrotoxicity induced by gentamicin was clearly evident with the decline in the activities of lactate dehydrogenase, alkaline phosphatase and N-acetyl-beta-D-glucosaminidase in the rat renal tissues. A significant decrease was also observed in the activities of the transmembrane enzymes upon gentamicin administration. Treatment with lipoic acid decreased lipid peroxidation thereby maintaining the antioxidant status of the cell. The activities of the renal and transmembrane enzymes were also restored on lipoic acid treatment. The study has highlighted the beneficial effects of lipoic acid against experimental aminoglycoside toxicity in rats rendered bacteremic.

The antioxidant EPC-K1 ameliorates brain injury by inhibiting lipid peroxidation in a rat model of transient focal cerebral ischaemia

BACKGROUND

Cerebral ischaemia-reperfusion injury is associated with the generation of reactive oxygen species during the early phases of reoxygenation. EPC-K1, a phosphate diester of vitamins C and E, has been reported to possess potent hydroxyl radical scavenging activity. This study was performed to investigate the effectiveness of EPC-K1 in attenuating cerebral ischaemia-reperfusion injury in a rat model of transient focal cerebral ischaemia.

METHOD

We evaluated the efficacy of EPC-K1 by measuring the concentration of cerebral thiobarbituric acid reactive substances (TBARS), an indicator of the extent of lipid peroxidation by free radicals, and infarct size in rats subjected to one hour of cerebral ischaemia and 4, 24, or 72 hours of reperfusion.

FINDINGS

EPC-K1 significantly reduced both the cerebral TBARS level and the infarct size in a rat model of transient focal cerebral ischaemia. These results indicate that EPC-K1 administration during the early stages of reperfusion ameliorates ischaemic brain injury by inhibiting lipid peroxidation.

INTERPRETATION

This report is the first to describe the protective mechanism of EPC-K1 by measuring both the TBARS level and infarct size in a rat model of transient focal cerebral ischaemia, and may suggest a potential clinical approach for the treatment of ischaemic cerebrovascular disease.

Age-dependent differences in the stimulation of lipid peroxidation in the heart of rats during immobilization stress

In order to investigate the possible reasons for age-related decrease in myocardium resistance to stress, we carried out a study of lipid peroxidation (LPO) stimulation features in the myocardium of adult (10-12 months) and aged (22-25 months) male Wistar rats during immobilization stress. In our studies of ascorbate-dependent LPO and induced chemiluminescence, we found that immobilization stress is accompanied by decreased efficiency in the induction of free radical processes in the heart of aged rats. An important cause of this phenomenon may be age-dependent changes in the catalytical properties of the cytosolic superoxide dismutase. The pathophysiological consequences of stress-related, age-dependent decreased efficiency of induction of free radical processes in the heart are discussed.

Hepatoprotective effect of Angelica archangelica in chronically ethanol-treated mice

Angelica archangelica (AAA) has been effectively used in folk medicines as a remedy against stomachal and intestinal disturbances, arthritic disease, etc. However, there is still lack of scientific proof about its antioxidant capability. This study aimed at investigating the effects of total AAA against chronic ethanol-induced hepatotoxicity. ICR mice were divided into five groups, each consisting of 10 animals. A single dose of ethanol (70%, 0.1 ml, p.o.) was used to induce hepatotoxicity in these mice which resulted in a significant elevation of the activities of serum GOT and GPT. Treatment of mice with AAA (10, 25, and 50 mg/kg p.o.) after 2 weeks ameliorated the ethanol-induced hepatotoxicity effects. Hepatotoxicity was evidenced by a significant increase in hepatic lipid peroxidation manifested as the presence of malondialdehyde. It was found that AAA inhibits the malondialdehyde formation in mouse liver homogenates both in vitro and in vivo. AAA is cytoprotective agent effective against chronic ethanol-induced hepatotoxicity, possibly through inhibition of the production of oxygen free radicals that cause lipid peroxidation, and hence indirectly protects the liver from oxidative stress.

Zinc-induced apoptosis in substantia nigra of rat brain: neuroprotection by vitamin D3

Accumulation of transition metals has been suggested to be responsible for the deteriorated nigrostriatal dopaminergic system in Parkinson's patients. In the present study, the mechanism underlying the zinc-induced neurotoxicity was investigated in the nigrostriatal dopaminergic system in vivo. Our 6-methoxy-8-paratoluene sulfonamide quinoline fluorescence study showed zinc translocation in the infused nigral cells after intranigral infusion of zinc. Furthermore, lipid peroxidation in the zinc-infused substantia nigra was consistently elevated 4 h to 7 d after the infusion. At the same time, an abrupt increase in cytosolic cytochrome c content in the infused substantia nigra was observed 4 h after zinc infusion and gradually decreased to basal levels 7 d after infusion. Both TUNEL-positive neurons and DNA fragmentation, indicatives of apoptosis, were detected in the zinc-infused substantia nigra. Furthermore, striatal dopamine content was reduced 7 d after the infusion. In attempt to prevent zinc-induced neurotoxicity, vitamin D3 was systemically administered. Zinc-induced increases in lipid peroxidation and cytosolic cytochrome c in the infused substantia nigra were prevented by this treatment. Moreover, zinc-induced reduction in striatal dopamine content was attenuated after vitamin D3 treatment. Our in vivo data suggest that zinc-induced oxidative stress may result in apoptosis followed by reduced dopaminergic function in the nigrostriatal dopaminergic system. Furthermore, vitamin D3 prevented zinc-induced oxidative injuries in the rat brain.

Experimental membrane-destructive model of cardiac arrhythmia

We propose a method for experimental modeling of cardiac arrhythmias. The method consists in intravenous injection of LPO inductors: 5% ascorbic acid (50 mg/kg), 1 min later 1% iron sulfate (10 mg/kg), and after the appearance of giant T waves on ECG infusion of 10% calcium chloride in a nonarrhythmogenic dose 100 mg/kg. Cardiac arrhythmias were induced in 100% animals. A significant relationship between increased permeability of erythrocyte membranes and development of fatal cardiac arrhythmias was detected. We assumed that this methodologically simple membrane-destructive model of cardiac arrhythmia is pathogenetically close to arrhythmogenesis in patients with coronary heart disease.

Lipoprotein oxidation, plasma total antioxidant capacity and homocysteine level in patients with multiple sclerosis

Free radical-mediated peroxidation of biological molecules, especially of lipids, is implicated in the pathogenesis of a number of diseases like multiple sclerosis. Low concentration of antioxidant vitamins: beta carotene, retinol, alpha tocopherol and ascorbic acid have been observed in serum or cerebrospinal fluid of multiple sclerosis patients. On the basis of these observations, we studied the potential lipoprotein oxidation and total antioxidant capacity in the pathogenesis of multiple sclerosis. Lipoprotein oxidizability for plasma in vitro, serum levels of autoantibodies against oxidized low-density lipoproteins, plasma total homocysteine levels with vitamin B12 and folate, and plasma total antioxidant capacity were measured in twenty four patients with multiple sclerosis and twenty four healthy sex- and age-matched person as control. In multiple sclerosis patients during an attack, a significant increase in both in vitro lipid oxidizability for plasma and in the levels of autoantibodies against oxidized low-density lipoproteins, and a strong decrease in plasma total antioxidant capacity were detected. Plasma total homocysteine levels were significantly higher in multiple sclerosis patients whose plasma vitamin B12 and folate levels were lower but not statistically significant, than controls. The present study indicates that lipoprotein oxidation may be important factor in the course of multiple sclerosis and in vitro measurements of plasma oxidation kinetics as an indication for lipoprotein oxidation might be useful as an additional tool for the clinical diagnosis of multiple sclerosis.

The nitric oxide donor molsidomine prevents ischemia/reperfusion injury of the adult rat small intestine

It is suggested that gastrointestinal mucosal blood flow depends on a balanced release of vasoactive substances from the endothelium. The present study investigated the effects of molsidomine on the small intestine after ischemia-reperfusion (I/R) injury in four groups of 10 rats each composed: (1) SO, sham operation; (2) untreated I/R; (3) ML, I/R plus molsidomine pretreatment; (4) L-NAME, I/R plus N-omega-nitro-L-arginine methyl ester pretreatment. Intestinal ischemia for 45 min and reperfusion for 60 min were applied. Ileum specimens were obtained to determine the tissue level of malondialdehyde (MDA) and histologic changes. Mean MDA levels in the SO, untreated I/R, ML, and L-NAME groups were 95.60 +/- 2.59, 136.90 +/- 4.35, 121.10 +/- 3.38, and 137.40 +/- 4.42 nmol/g wet tissue, respectively. Although the MDA level in the ML group was higher than in the SO group ( P < 0.0001), it was significantly lower compared to the untreated I/R and L-NAME groups ( P < 0.0001, P < 0.0001). Mucosal injury scores (MIS) in groups 1-4 were 0.2 +/- 0.42, 3.9 +/- 0.73, 1.5 +/- 0.70, and 4.1 +/- 0.56, respectively. In group 3 the MIS was significantly lower than in groups 2 and 4 ( P < 0.0001, P < 0.0001). Molsidomine plays a role in attenuating reperfusion injury of the small intestine by depression of tissue MDA levels and MIS and regulates post-ischemic intestinal perfusion while restoring the intestinal microcirculatory blood flow and histologic injury.

Age-related oxidative inactivation of Na+, K+-ATPase in rat brain crude synaptosomes

The study was undertaken to examine the status of Na(+), K(+)-ATPase in aged rat brain and to verify if any alteration of this enzyme in aged brain could be related to an oxidative damage. The crude synaptosomes from rat brain were exposed in vitro to an oxidative stress in the form of a combination of Fe(2+) (100 microM) and ascorbate (2 mM) for up to 2 h when increased lipid peroxidation (nearly four-fold), extensive protein carbonyl formation and a marked decrease of Na(+), K(+)-ATPase activity (approximately 88%) were observed. All these changes were prevented by the presence of a chain-breaking anti-oxidant, butylated hydroxytoluene (0.2 mM), in the incubation mixture. When the same crude synaptosomal membranes from the young (4-6 months) and aged (18-22 months) rat brains were analysed, a significant reduction of Na(+), K(+)-ATPase activity (nearly 48%) along with significantly elevated levels of lipid peroxidation products and protein carbonyls could be detected in the aged animals in comparison to young ones. The latter data in combination with the results of in vitro experiments imply that the age-related decline of rat brain Na(+), K(+)-ATPase activity is presumably the consequence of an enhanced oxidative damage in aging brain

Predominant effects of Polypodium leucotomos on membrane integrity, lipid peroxidation, and expression of elastin and matrixmetalloproteinase-1 in ultraviolet radiation exposed fibroblasts, and keratinocytes

BACKGROUND

Polypodium leucotomos has been reported to have antioxidant, anti-inflammatory and photoprotective properties. Exposure of skin to ultraviolet (UV) radiation can lead to deposition of excessive elastotic material, reduction in collagen, and increased expression of matrix metalloproteinases (MMPs).

OBJECTIVE

The goal of this research was to determine the effects of P. leucotomos in the absence or presence of UVA or UVB radiation on membrane damage, lipid peroxidation, and expression of elastin and MMP-1 in fibroblasts and keratinocytes, respectively.

METHODS

Fibroblasts and keratinocytes, respectively, were irradiated by a single exposure to UVA (0.6, 1.8 or 3.6 J) or UVB radiation (0.75, 2.5 or 7.5 mJ), and then incubated with, or without, P. leucotomos (0.01, 0.1 and 1%) and examined for membrane damage, lipid peroxidation, expression of elastin (protein levels) and MMP-1 (protein levels or MMP-1 promoter activity).

RESULTS

UV radiation did not significantly alter membrane integrity, lipid peroxidation or MMP-1 expression, but increased elastin expression. P. leucotomos significantly improved membrane integrity, inhibited lipid peroxidation, increased elastin expression, and inhibited MMP-1 expression in both fibroblasts, and keratinocytes. The effects of P. leucotomos predominated in the presence of UVA or UVB in both fibroblasts and keratinocytes, respectively, with the exception of inhibition of MMP-1 protein levels in fibroblasts only in combination with UV radiation.

CONCLUSION

Lower concentration of P. leucotomos (lower than 0.1%), may be beneficial in preventing photoaging by improving membrane integrity and inhibiting MMP-1, without increasing elastin expression. Higher concentration (greater than 0.1%) of P. leucotomos may reverse the loss of normal elastic fibers associated with intrinsic aging.

Does sodium nitroprusside reduce lung injury under cardiopulmonary bypass?

OBJECTIVE

We hypothesized that direct pulmonary arterial infusion of sodium nitroprusside (SNP) would ameliorate lung injury under cardiopulmonary bypass.

METHODS

Experiments were performed on 12 adult mongrel dogs of both sexes weighing 20-28 kg. The animals were randomly divided into two groups of six animals each. All animals were subjected to total cardiopulmonary bypass (CPB) and moderate hypothermia (28 degrees C core temperature). During total CPB, the aorta was clamped together with the pulmonary artery to prevent any antegrade flow to the lungs. After cardioplegic arrest for 120 min, the animals were rewarmed, weaned from CPB, and their condition stabilized for another 90 min. After the release of the aortic cross-clamp, the dogs received either a 5% glucose solution as a placebo (group I) or SNP (0.5 microg/kg per min) (group II), both infused into the pulmonary arterial line. The infusion was stopped after 60 min. To measure lung tissue malondialdehyde (MDA), water content and polymorphonuclear leukocytes count, lung tissue samples were taken before CPB and after weaning from CPB. In addition, alveolar-arterial oxygen difference (AaDO(2)) for tissue oxygenation was calculated by obtaining arterial blood gas samples.

RESULTS

Values of MDA before CPB of 42.0+/-5.3 nmol/g of tissue rose to 67.6+/-5.7 nmol/g of tissue after weaning from CPB in group I (P=0.028). In group II MDA values also increased from 43.1+/-4.3 to 52.4+/-5.7 nmol MDA/g of tissue after weaning from CPB (P=0.046). The MDA increase in group II after CPB was found to be significantly lower than that for group I (P=0.004). The wet-to-dry lung weight ratio in the sodium nitroprusside group was 5.1+/-0.2, significantly lower than in the control group (6.8+/-0.4), (P=0.01). AaDO(2) increased significantly in group I (P=0.028). There was no statistically significant difference (P=0.065) between groups I and II. During histopathological examination it was observed that neutrophil counts in the lung parenchyma rose significantly after CPB in both groups. The increase in group I was significantly larger than that in group II (P<0.001).

CONCLUSIONS

The results represented in our study indicate that pulmonary arterial infusion of sodium nitroprusside during reperfusion can reduce lung injury under cardiopulmonary bypass.

A free radical initiator, 2,2'-azobis (2-aminopropane) dihydrochloride enhances hyperthermia-induced apoptosis in human uterine cervical cancer cell lines

Hyperthermia-induced apoptosis and its enhancement in the presence of a temperature-dependent free radical initiator, 2,2'-azobis (2-aminopropane) dihydrochloride (AAPH) were examined in human uterine cervical cancer cell lines, CaSki and HeLa. When both cell lines were treated with hyperthermia at 44 degrees C for 60 min, minimal apoptosis was observed. When combined with nontoxic AAPH (50mM), significant enhancement of apoptosis was observed, where the initial rate of free radical formation was about twice as high than that at 37 degrees C. Augmentation of the growth delay, lipid peroxidation (LPO), activation of caspase-3 and increase in [Ca2+]i were also observed after the combined treatment. A water-soluble vitamin E, Trolox, blocked the increase in [Ca2+]i and an intracellular Ca2+ chelator, BAPTA-AM, prevented the DNA fragmentation induced by the combination. Cytochrome c release was also revealed by fluorescence microscopy. However, no significant change in mitochondrial membrane potential and expression of Bax and Bcl-2 was observed. A slight increase in Fas expression was observed only in CaSki cells after the combined treatment. These results indicate that hyperthermia and AAPH induce enhanced apoptosis and subsequent cell killing via two pathways; a pathway dependenton increase in LPO and [Ca2+]i, and a pathway associated with cytochrome c release and subsequent caspase activation without changes of mitochondrial membrane potential and Bax/Bcl-2 expression in these cell lines. Since it is known that cancer cells are generally resistant to physical and chemical stress-induced apoptosis, free radical generators like AAPH appear to be a useful thermosensitizer for hyperthermic cancer therapy.

Immunochemical detection of a novel lysine adduct using an antibody to linoleic acid hydroperoxide-modified protein

We have previously prepared the polyclonal antibody to the 13-hydroperoxyoctadecadienoic acid-modified protein (13Ab) (Kato et al. 1997. J. Lipid Res. 38: 1334-1346), however, the epitopes have not yet been structurally identified. In this study, we identified a novel amide-type adduct as one of the major epitopes of 13Ab and characterized the endogenous formation. Upon incubation of the lysine derivative with peroxidized linoleic acid, the formation of N epsilon -(azelayl)lysine (AZL) was confirmed using liquid chromatography-mass spectrometry. The chemically synthesized azelayl protein was significantly recognized by 13Ab. The peroxidation products of different polyunsaturated fatty acids also generated several analogous carboxyalkylamide-type adducts to AZL by the reaction with the lysine derivative, whereas 13Ab specifically recognized AZL, suggesting that the AZL moiety may be one of the major epitopes of 13Ab. The immunoreactive materials of 13Ab were immunohistochemically detected in atherosclerotic lesions from hypercholesterolemic rabbits. More strikingly, the immunoreactivity was significantly enhanced when the sections were treated with alkali or phospholipase A2 for hydrolyzing the ester bonds prior to the staining. These results suggest that the lipid hydroperoxide-derived carboxylic adducts, such as AZL, and their esters linked with phospholipids may be generated in vivo and involved in the pathogenesis of atherosclerosis associated with oxidative stress.

Platelet aggregation, blood viscosity and serum lipids in hypertensive and obese children

A group of 35 patients (median age 15.5 years, range 8-17 years) with juvenile essential hypertension, 15 with body mass index (BMI kg/m(2)) <25 and 20 with BMI >25, as well as 35 age and sex matched controls (BMI <25 n=20; BMI >25 n=15) were investigated to study the role of hypertension and obesity, separately and in combination, on in vitro platelet aggregation, blood and plasma viscosity, plasma lipid concentrations and lipid peroxidation as well as nitric oxide (NO) production. Obese children (hypertensive and controls) had significantly higher concentrations of total cholesterol and triglycerides. The levels of high density lipoprotein (HDL)-cholesterol were lower in obese hypertensive children than their non-obese counterparts. There was a significant increase in platelet aggregation and a decrease in NO levels in hypertensive patients (obese and non-obese) reflecting a significant negative correlation (r=-0.553 and -0.530, n=35; P<0.01, respectively). However, an increased tendency to aggregation was also evident in obese normotensive patients. A significant positive correlation was observed between the platelet aggregation and BMI (r=0.501, n=35; P<0.01). Plasma free thiols were decreased in hypertensive children independent of their BMI. An increased lipid peroxidation and higher blood and plasma viscosity were found only in obese patients with hypertension. Multivariate analysis revealed significant interactions in the effects of obesity and hypertension on platelet aggregation and thiol oxidation.

CONCLUSION

in obese children an increased platelet aggregation and oxidative insult contribute to the development of hypertension and to the promotion of vascular damage.

Female rats are protected against oxidative stress during copper deficiency

BACKGROUND

Copper deficiency induces a dramatic decrease of superoxide dismutase activity and leads to alteration of antioxidant defense systems.

METHODS

and

OBJECTIVE

Experiments were conducted in weanling male, intact and ovariectomized female rats, fed either a copper-adequate or copper-deficient diet for seven weeks, in order to determine whether endogenous estrogen could modulate oxidative stress and the severity of copper-deficiency.

RESULTS

Feeding male rats a copper-deficient diet induced typical signs of copper deficiency, such as decreased hepatic copper, growth retardation, anemia, heart hypertrophy, pancreas atrophy and hypercholesterolemia. Furthermore, copper deficiency increased the amount of lipid peroxidation products in the heart, liver and pancreas following in vitro iron induction. Although levels of hepatic copper in copper-deficient females were similar to those of their male counterparts, the females were partially protected from the adverse effects of the deficiency (no growth retardation, less severe anemia, lesser extent of lipid peroxidation). Thus, female rats are provided with a greater degree of protection against oxidative damage than males. However, females did not appear to be protected against pancreas atrophy, heart enlargement and hypercholesterolemia induced by copper deficiency. This observed partial protection of females was lost after ovariectomy as shown by decreased body weight and hematocrit, heart enlargement and higher tissue peroxidation in ovariectomized females compared to intact females.

CONCLUSIONS

The results suggest that the partial protection of copper deficient females is related to the antioxidant properties of estrogens. The protective action of estrogen against oxidative stress is of particular importance when antioxidant defenses are decreased as shown in this experimental model.

Supplementation of vitamin E and selenium prevents hyperoxaluria in experimental urolithic rats

Renal injury is considered as one of the prerequisites for calcium oxalate retention. In order to determine the role of lipid peroxidation related effects for hyperoxaluria, we evaluated the alterations in lipid peroxidation, antioxidants and oxalate synthesizing enzymes in lithogenic rats with response to vitamin E + selenium treatment. In kidney of lithogenic rats, the level of lipid peroxidation and the activities of oxalate synthesizing enzymes were found to be increased whereas the levels/activities of non-enzymatic and enzymatic antioxidants were found to be decreased. The urinary excretion of both oxalate and calcium were significantly elevated. Supplementation of lithogenic rats with vitamin E + selenium decreased the levels of lipid peroxides and the activities of oxalate synthesizing enzymes like glycolic acid oxidase (GAO), lactate dehydrogenase (LDH), xanthine oxidase (XO) with a concomitant increase in the activities of enzymatic antioxidants like superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glucose-6-phosphate dehydrogenase (G6PDH) and increased levels of non-enzymatic antioxidants like ascorbic acid, alpha-tocopherol and reduced glutathione (GSH). The urinary excretion of oxalate and calcium were normalized. The antioxidants vitamin E + selenium thereby protected from hyperoxaluria.