Oxidative stress, metabolism of ethanol and alcohol-related diseases

Alcohol-induced oxidative stress is linked to the metabolism of ethanol. Three metabolic pathways of ethanol have been described in the human body so far. They involve the following enzymes: alcohol dehydrogenase, microsomal ethanol oxidation system (MEOS) and catalase. Each of these pathways could produce free radicals which affect the antioxidant system. Ethanol per se, hyperlactacidemia and elevated NADH increase xanthine oxidase activity, which results in the production of superoxide. Lipid peroxidation and superoxide production correlate with the amount of cytochrome P450 2E1. MEOS aggravates the oxidative stress directly as well as indirectly by impairing the defense systems. Hydroxyethyl radicals are probably involved in the alkylation of hepatic proteins. Nitric oxide (NO) is one of the key factors contributing to the vessel wall homeostasis, an important mediator of the vascular tone and neuronal transduction, and has cytotoxic effects. Stable metabolites--nitrites and nitrates--were increased in alcoholics (34.3 +/- 2.6 vs. 22.7 +/- 1.2 micromol/l, p < 0.001). High NO concentration could be discussed for its excitotoxicity and may be linked to cytotoxicity in neurons, glia and myelin. Formation of NO has been linked to an increased preference for and tolerance to alcohol in recent studies. Increased NO biosynthesis also via inducible NO synthase (NOS, chronic stimulation) may contribute to platelet and endothelial dysfunctions. Comparison of chronically ethanol-fed rats and controls demonstrates that exposure to ethanol causes a decrease in NADPH diaphorase activity (neuronal NOS) in neurons and fibers of the cerebellar cortex and superior colliculus (stratum griseum superficiale and intermedium) in rats. These changes in the highly organized structure contribute to the motor disturbances, which are associated with alcohol abuse. Antiphospholipid antibodies (APA) in alcoholic patients seem to reflect membrane lesions, impairment of immunological reactivity, liver disease progression, and they correlate significantly with the disease severity. The low-density lipoprotein (LDL) oxidation is supposed to be one of the most important pathogenic mechanisms of atherogenesis, and antibodies against oxidized LDL (oxLDL) are some kind of epiphenomenon of this process. We studied IgG oxLDL and four APA (anticardiolipin, antiphosphatidylserine, antiphosphatidylethanolamine and antiphosphatidylcholine antibodies). The IgG oxLDL (406.4 +/- 52.5 vs. 499.9 +/- 52.5 mU/ml) was not affected in alcoholic patients, but oxLDL was higher (71.6 +/- 4.1 vs. 44.2 +/- 2.7 micromol/l, p < 0.001). The prevalence of studied APA in alcoholics with mildly affected liver function was higher than in controls, but not significantly. On the contrary, changes of autoantibodies to IgG oxLDL revealed a wide range of IgG oxLDL titers in a healthy population. These parameters do not appear to be very promising for the evaluation of the risk of atherosclerosis. Free radicals increase the oxidative modification of LDL. This is one of the most important mechanisms, which increases cardiovascular risk in chronic alcoholic patients. Important enzymatic antioxidant systems - superoxide dismutase and glutathione peroxidase - are decreased in alcoholics. We did not find any changes of serum retinol and tocopherol concentrations in alcoholics, and blood and plasma selenium and copper levels were unchanged as well. Only the zinc concentration was decreased in plasma. It could be related to the impairment of the immune system in alcoholics. Measurement of these parameters in blood compartments does not seem to indicate a possible organ, e.g. liver deficiency.

Changes of superoxide dismutase, catalase and glutathione peroxidase in the corneal epithelium after UVB rays. Histochemical and biochemical study

In this study, the effects of UVA and UVB rays on antioxidant enzymes (superoxide dismutase, glutathione peroxidase, catalase) were examined in the corneal epithelium. The corneas of albino rabbits were irradiated with a UV lamp generating UVA (365 nm wavelength) or UVB rays (312 nm wavelength), 1 x daily for 5 min, from a distance of 0.03 m, over 4 days (shorter procedure) or 8 days (longer procedure). In contrast to UVA rays, which did not evoke significant disturbances, UVB rays changed the activities of antioxidant enzymes. The longer repeated irradiation with UVB rays was performed, the deeper the observed decrease in antioxidant enzymes. The shorter procedure evoked a more profound decrease of glutathione peroxidase and catalase (the enzymes cleaving hydrogen peroxide) than of superoxide dismutase, an enzyme scavenging superoxide radical and producing hydrogen peroxide during the dismutation reaction of a superoxide free radical. This may contribute to an insufficient hydrogen peroxide cleavage at the corneal surface and danger to the cornea from oxidative damage. After the longer procedure (UVB rays), the activities of all antioxidant enzymes were very low or completely absent. In conclusion, repeated irradiation of the cornea with UVB rays evokes a deficiency in antioxidant enzymes in the corneal epithelium, which very probably contributes to the damage of the cornea (and possibly also deeper parts of the eye) from UVB rays and the reactive oxygen products generated by them.

[Fatty acid composition and parameters of VLDL and LDL in persons with dyslipidemia]

BACKGROUND

Oxidatively modified LDL play an important role in the pathogenesis of endothelial dysfunction, initiation and development of atherosclerosis and stability of the atheromatous plaque. The increased oxidative stress is apparent from a number of deviations, which are part of the insulin resistance syndrome (hypertension, hypoalphacholesterolaemia, diabetes and hyperlipoproteinaemia). The objective of the work was to examine the degree of oxidation and oxidability of LDL and VDL in subjects with dyslipidaemia.

METHODS AND RESULTS

In 40 subjects with dyslipidaemia, defined as a triglyceride concentration above 2.30 mmol/l and a drop of HDL cholesterol below 0.90 mmol/l, the authors assessed the fatty acid profile in plasma lipid classes and LDL by capillary gas chromatography. Lipoperoxidation in VLDL and LDL was examined by the method of kinetics of conjugated dienes according to Esterbauser. The results were compared with a group of healthy controls. The group of dyslipidaemic subjects had higher concentrations of NEFA, IRI, blood sugar and uric acid. In these subjects the concentration of conjugated dienes in VLDL was significantly higher and the lag stage in VLDL and LDL was reduced. Both groups differed as to the composition of VLDD and LDL. The group of dyslipidaemic subjects had a higher concentration of cholesterol, phospholipids, triglycerides and apolipoprotein B. A constant finding in the fatty acid profile of all lipid classes was a raised concentration of palmitoleic acid and reduced linoleic acid concentration.

CONCLUSIONS

Dyslipidaemic subjects have, as compared with a control group, higher NEFA, IRI and uric acid concentrations. Furthermore they differed not only by the composition of VLDL and LDL but also by a higher degree of VLDL oxidation and reduced resistance to lipoperoxidation of VLDL and LDL particles. A consistent finding in the fatty acid profile was an increased level of palmitoleic acid in all plasma lipid classes and LDL and a drop of linoleic acid in phosphatidylcholine LDL and plasma cholesterolesters.

Effect of the carbon source on assessment of degrading bacteria with the spread-plating technique during in situ bioremediation

Spread-plating belongs to traditional microbiological methods employed for quantification of subsurface microflora during bioremediation projects in the Czechia. Concentration of degrading organisms is estimated from the number of colonies grown on agar plates supplied with contaminant as the sole carbon source. The data obtained during in situ bioremediation of the Dacice site contaminated by cutting oil suggests that changes in the composition of the carbon source in the subsurface may cause a discrepancy between laboratory data and situation in subsurface.

[Effect of losartan and enalapril on urinary excretion of 8-isoprostane in experimental nephrotic syndrome]

BACKGROUND

Increased permeability of glomerular capillary wall in adriamycin nephropathy may be mediated by increased generation of free radicals and possibly also by the non-enzymatic production of isoprostanes induced by oxidative stress. ACE inhibitors may reduce proteinuria, possibly due to the decrease of intraglomerular pressure and increased permselectivity of the glomerular capillary wall. These effects may be partly mediated by the inhibition of the degradation of kinins. It is not clear if newly available angiotensin II antagonists have the same antiproteinuric and renoprotective effects.

METHODS AND RESULTS

We compared the effect of an ACE inhibitor (enalapril, 0.4 mg/kg bw i.p. daily for 3 weeks) and angiotensin II antagonist (losartan, 2 mg/kg bw in the same way) on experimental nephrotic syndrome induced in rats by the administration of adriamycin (5 mg/kg bw i.v. in a single dose). To elucidate the potential differences between these two drugs we also measured total malondialdehyde in blood and urinary excretion some eicosanoids and their metabolites (TxB2, 6-keto-PGF1alfa, bicyclo-PGE2 and 8-isoprostane). Proteinuria increased in adriamycin treated rats after 3 weeks from 0.18 +/- 0.01 to 0.44 +/- 0.14 g/mmol creat, p < 0.01. This increase was not prevented by losartan (increase from 0.18 +/- 0.12 to 0.50 +/- 0.11 g/mmol creat, p < 0.05), but tended to be partly blunted by enalapril (increase from 0.20 +/- 0.10 to only 0.32 +/- 0.08 g/mmol creat, p < 0.05). Similarly there was no increase of serum cholesterol, only in enalapril treated rats. On the other hand, both losartan (1.27 +/- 0.13 vs. 1.91 +/- 0.30 mumol/l, p < 0.05) and enalapril (0.93 +/- 0.06 mumol/l, p < 0.001) prevented adriamycin induced increase of total MDA in serum, but urinary excretion of 8-isoprostane was increased in nephrotic rats treated by losartan compared to controls. Enalapril induced increase of urinary excretion of bicyclo-PGE2 (4.32 +/- 0.62 vs. 1.66 +/- 0.81 ng/mmol creat, p < 0.001) was possibly mediated by kinins. There was no significant difference in the urinary excretion of other eicosanoids between different groups, but proteinuria correlated positively with urinary excretion of 8-isoprostane (p < 0.01). Proteinuric rats had also significantly higher urinary excretion of 8-isoprostane than non-proteinuric rats (44.8 +/- 7.1 vs. 26.7 +/- 3.4 ng/mmol. creat, p < 0.05).

CONCLUSIONS

Our data suggest that proteinuria in adriamycin nephropathy may mainly depend on free radical generation and the formation of 8-isoprostane. Haemodynamic parameters (glomerular pressure) do not seem to be so important. The mild antiproteinuric effect of enalapril may suggest a contributory role of the inhibition of kinin degradation in this model of nephrotic syndrome.

[Plasma leptin levels in patients with kidney diseases of various etiologies]

BACKGROUND

Leptin is a new hormone influencing food intake, energy expenditure and body weight. This protein is produced by adipocytes, exerts its effects on brain, endocrine pancreas and other organs by activating transmembrane receptors and is cleared from plasma mainly by the kidneys. The aim of our study was to compare plasma concentrations of leptin in our nephrological out-patients and controls.

METHODS AND RESULTS

We examined 36 diabetic patients with various stages of nephropathy, 12 males with nephrotic syndrome due to membranous nephropathy, 15 dialysis patients and 11 controls. Leptin was assessed in plasma by ELISA. There was a significant difference between plasma levels of leptin in males and females (7.7 +/- 11.4 vs 17.6 +/- 17.3, p < 0.001) and in dialysis and non-dialysis patients (19.6 +/- 16.5 vs 10.7 +/- 14.5, p < 0.05). There was also a difference between dialysed and non-dialysed men (15.1 +/- 16.2 vs 5.9 +/- 9.2, p < 0.05). We found no difference between men with and without nephrotic syndrome and between BMI or age. There was a positive correlation of leptin with diabetic and non-diabetic women. There was positive correlation of P-leptin with serum creatinine in non-dialysed women (r = 0.68, p < 0.001) and a negative correlation with S-albumin in nephrotic men (r = -0.65, p < 0.05).

CONCLUSIONS

Women have higher plasma leptin concentrations than men and dialysis patients have higher concentrations than non-dialysed patients. Apart from the positive correlation with S-creatinine in non-dialysed women. There was positive correlation with S-albumin in nephrotic men there were no correlations with renal function, BMI, age, S-cholesterol, S-triglycerides and S-albumin.

ICRF-187 (dexrazoxan) protects from adriamycin-induced nephrotic syndrome in rats

BACKGROUND

Reactive oxygen species produced during metabolism of adriamycin are purported to play an important role in the pathogenesis of experimental adriamycin nephropathy in rats. ICRF-187 (dexrazoxan, Cardioxan), an iron chelator, has been shown to inhibit adriamycin-induced formation of hydroxyl radical and to decrease adriamycin cardiotoxicity in oncological patients. The aim of our study was to assess the putative protective role of ICRF-187 in adriamycin nephropathy by evaluating the possible participation of free radicals in its pathogenesis.

METHODS

We examined five experimental groups. Group A, received a single dose of adriamycin (5 mg/kg bw i.v.), group CA was given a single dose of ICRF-187 (100 mg/kg bw i.v.) before adriamycin administration, group CCA received a single dose of ICRF-187 (100 mg/kg bw i.v.) before adriamycin administration followed by three weekly intraperitoneal injections (100 mg/kg bw) ICRF-187. Group CC received one dose of ICRF-187 (100 mg/kg bw i.v.) followed by three weekly intraperitoneal injections of ICRF-187, and group N served as control receiving saline. Common biochemical parameters, malondialdehyde (MDA) and antioxidant enzymes (glutathione peroxidase--GPx and superoxide dismutase--SOD) in blood and kidney homogenates were measure and histology of the kidney was studied after the rats were sacrificed.

RESULTS

Full-blown nephrotic syndrome developed after 3 weeks only in A rats. Nephrotic syndrome was completely prevented in all ICRF-187 treated rats (CA, CCA). Proteinuria was significantly increased in A rats (108.2 + 48.4 mg/l of glomerular filtrate) compared with CA (12.4 + 6.8 mg/l, P < 0.0001) and with N (6.1 + 3.5 mg/l, P < 0.0001). Total MDA in erythrocytes was significantly increased only in A rats (1.7 + 0.3 micromol/l) and was completely normalized by ICRF-187 in CA (1.1 + 0.2 micromol/l, P < 0.001). Total TBARS and MDA in kidney homogenates were significantly elevated in groups with repeated administration of ICRF-187 (CC and CCA rats) compared to N, CA, A groups. Activity of GPx and SOD in kidney homogenate and in erythrocytes was not significantly increased by ICRF-187 in adriamycin treated rats. Histologic changes in A rats resembled minimal change nephropathy with fusion of foot processes and hyaline casts in tubules. There was only minimal mesangial proliferation and perivascular mast cell infiltrates in all groups of ICRF-187-treated rats.

CONCLUSIONS

We conclude that ICRF-187, probably by chelation iron, completely protected rats from adriamycin-induced nephrotic syndrome. It supports the role of iron-mediated reactive oxygen species in the development of this type of glomerular injury. However, repeated administration of ICRF-187 alone is able to increase parameters of oxidative stress in the kidney.

The influence of chronic moderate ethanol administration on NADPH-diaphorase (nitric oxide synthase) activity in rat brain

Nitric oxide synthase (NOS), the enzyme with reduced nicotinamide-adenine dinucleotide phosphate (NADPH)-diaphorase activity, generates nitric oxide (NO) which is an important bioregulatory molecule in the nervous, immune, and cardiovascular systems. NOS is linked to non-adrenergic non-cholinergic (NANC) neuronal pathways and modulation of the N-methyl-D-aspartate receptors, yet its modification by ethanol has been little explored. A possible modification by chronic ethanol administration of activity and/or localization of NADPH-diaphorase (NO-synthase) in rat brain may thus provide the pathogenic basis of alcohol-induced brain injury. When female Wistar rats were treated chronically with ethanol for 50 days, the NADPH-diaphorase staining of granular neurons and neurons located in the molecular layer of the cerebral cortex was significantly reduced. Chronic ethanol consumption led to a significant reduction in NADPH-diaphorase staining in the superficial layers of the superior colliculus. The number of NADPH-diaphorase-positive neurons was significantly reduced (P < 0.001) in the stratum zonale and stratum griseum superficiale (by 42.3-65.6% of control values). This could alter synaptic processes in the highly organized structures involved in oculomotor and somatic motor coordination and thus contribute to the motor disturbances which are associated with alcohol abuse.

The effect of quinolinate on rat brain lipid peroxidation is dependent on iron

Quinolinate, an endogenous excitotoxic metabolite of tryptophan with affinity to the N-methyl-D-aspartate type of glutamate receptor, is known as a stimulator of lipid peroxidation in vitro [Neurochem. Res. (1991) 16, 1139-1143]. To analyse the mechanism of this quinolinate toxicity we used the thiobarbituric acid test to measure malondialdehyde in homogenates of rat cerebral hemispheres incubated in air at 37 degrees C for 30 min in the presence of 0.015-15.0 mM quinolinate, endogenous iron or 0.5-2.0 microM FeSO4 and with or without 250 microM ascorbate. Quinolinate in the concentrations of 0.15-2.5 mM stimulated lipid peroxidation in the homogenates in the presence of 0.5-2.0 microM Fe2+. However, quinolinate concentrations higher than 3.0 mM inhibited the lipid peroxidation at all the tested concentrations of iron. In the presence of a potent iron chelator (10 microM deferoxamine) quinolinate completely failed to induce lipid peroxidation in rat brain homogenates. Spectral analysis revealed that quinolinate is able to form a complex with Fe2+. The results suggest that quinolinate does not have a direct peroxidative effect, but that it modulates lipid peroxidation via its interaction with iron.

The influence of cyclosporin on lipid peroxidation and superoxide dismutase in adriamycin nephropathy in rats

Cyclosporin A (CsA) was shown to reduce proteinuria in nephrotic syndrome, but its potential to increase lipid peroxidation may play a role in cyclosporin nephrotoxicity. The influence of cyclosporin treatment on the lipid peroxidation (assessed as malondialdehyde (MDA) in plasma and kidney homogenates using HPLC and reaction with thiobarbituric acid) and the activity of superoxide dismutase (SOD) in erythrocytes was studied in rats with nephrotic syndrome induced by single intravenous injection of adriamycin. Rats with nephrotic syndrome treated from the beginning with cyclosporin had lower proteinuria than untreated nephrotic rats. Free MDA in blood and kidney homogenates was significantly elevated in untreated nephrotic rats in comparison with controls. Activity of SOD in erythrocytes was significantly elevated in nephrotic rats treated with cyclosporin (113.40 +/- 34.31 mU/10(6) erythrocytes) in comparison with the control group (55.63 +/- 9.90 mU/10(6) erythrocytes, p < 0.001), rats treated with cyclosporin (65.7 +/- 17.49 mU/10(6) erythrocytes, p < 0.01) and untreated nephrotic rats (65.07 +/- 17.49 mU/10(6) erythrocytes, p < 0.001). In conclusion, cyclosporin reduced proteinuria in rats with mild adriamycin nephropathy (similar to human minimal change disease). Cyclosporin also partially counteracted adriamycin-induced lipid peroxidation probably due to the stimulation of antioxidant enzyme SOD. The possible contribution of decreased lipid peroxidation to the antiproteinuric effect of cyclosporin deserves further study.

Activity of the antioxidant enzymes superoxide dismutase and glutathione peroxidase in fetal erythrocytes

It is generally accepted that the balance between the formation and inactivation of reactive oxygen species may be abolished within the perinatal period, as a consequence of rapid changes in tissue oxygen concentration and the development of antioxidant defence enzyme activities. We studied the ontogeny of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx) in fetal blood samples. The activity of SOD in fetal erythrocytes taken in the 17th gestational week was the same as that in erythrocytes of healthy blood donors. On the other hand, GPx activity was significantly lower between the 17th and 25th gestational week and at the time of delivery, compared with the healthy adult control. Our results suggest that the supposed underdevelopment of the antioxidant system in the lungs or in the other organs of premature infants cannot be monitored by SOD and GPx activities in erythrocytes, because these reach adult levels before the 17th week for SOD and from the 26th to the 35th gestational week for GPx, with lower levels from the 17th to the 25th week and at term.

The influence of pefloxacine on experimental adriamycin-induced nephrotic syndrome in rats

Initial reports on antiproteinuric effect of pefloxacine in small groups of patients with minimal-change nephropathy (MCN) and focal and segmental glomerulosclerosis (FSGS) have not been confirmed in other papers. To assess its antiproteinuric effect in experimental animals we administered pefloxacine to rats with adriamycin nephropathy showing morphological changes resembling human minimal-change disease or focal segmental glomerulosclerosis, and clinically with full-blown nephrotic syndrome. Pefloxacine treatment was at least partially effective in preventing further increase of proteinuria in rats with adriamycin nephropathy. The mechanism of this effect remains unclear and deserves further studies concentrating on the glomerular cytokine network and glomerular production of reactive oxygen species.

[Lipid peroxidation and activity of antioxidative enzymes in patients with multiple myeloma]

BACKGROUNDS

Reactive oxygen species and other free radicals are known to be the mediators of phenotypic and genotypic changes that lead from mutation to neoplasia. The imbalance in tumor cell antioxidant defense mechanism can influence also the sensitivity to cytoreductive therapy. In erythrocytes it can results to hemolysis which is one of pathogenetic mechanisms of anemia in cancer patients.

METHODS AND RESULTS

We investigated the parameters of lipid peroxidation (malondialdehyde-MDA) and antioxidant enzymes here represented by superoxide dismutase (SOD) and glutathione peroxidase (GPx) in multiple myeloma. Nine patients of various clinical stage and activity of disease were studied. A significant higher concentration of total MDA in plasma (1.20 +/- 0.24 mumol/l v.s. 0.64 +/- 0.22 mumol/l, p < 0.0001) as well as in erythrocytes (2.72 +/- 0.81 mumol/l v.s. 1.03 +/- 0.44 mumol/l, p < 0.0001) was found comparing to the control group. The levels of free MDA in plasma (0.31 +/- 0.09 mumol/l v.s. 0.49 +/- 0.17 mumol/l, p < 0.05) and in erythrocytes (0.29 +/- 0.20 mumol/l v.s. 0.59 +/- 0.22 mumol/l, p < 0.001) were decreased in myeloma patients. A significantly lower activity of GPx (19.17 +/- 4.07 U/g v.s. 23.26 +/- 3.61 U/g Hb, p < 0.05) and SOD (1882.46 +/- 181.73 U/g v.s. 2347.13 +/- 502.51 U/g Hb, p < 0.05) in erythrocytes were found.

CONCLUSIONS

We didn't observe evident relationship between the concentration of MDA or activities of SOD and GPx and either the stage of disease or level and type of paraprotein. We can conclude, that higher concentration of total MDA as a parameter of lipid peroxidation, is significantly increased in patients with multiple myeloma. It could be consequence of impaired antioxidant defence. These results propose possible role of free radicals with reduced antioxidant activity of SOD and GPx in multiple myeloma. As we can consider the role of free radicals in pathogenesis of malignant proliferation, prognostic value and the change during the course of therapy should by studied.

Lipid peroxidation and antioxidant enzymes in CAPD patients

The mechanisms of free-radical injury include reactions with proteins, nucleic acids, and polysaccharides; and covalent binding to membrane components and initiation of lipid peroxidation. Cells have developed antioxidant defense to prevent free-radical injury including superoxide dismutase (SOD) and glutathione peroxidase (GPx). Significantly higher concentrations of total malondialdehyde (MDA) in plasma (1.22 +/- 0.42 vs. 0.64 +/- 0.22 micromol/L, p < 0.0001) as well as erythrocytes (2.56 +/- 1.28 vs. 1.03 +/- 0.44 micromol/L, p < 0.0001) of the CAPD patients were found when compared to the control group. The free MDA in plasma and the erythrocytes do not differ significantly in continuous ambulatory peritoneal dialysis (CAPD) patients and the control group. A significantly lower activity of GPx in erythrocytes of CAPD patients (17.85 +/- 2.63 U/g Hb vs. 23.26 +/- 3.61 U/g Hb, p < 0.0001) was found when compared to the control group, but the SOD activity in erythrocytes is not different (2272.36 +/- 579.92 U/g Hb vs. 2347.13 +/- 502.51 U/g Hg, NS). Our results show an increase of total MDA in erythrocytes and plasma. MDA is the product of lipid peroxidation with decreasing activity of GPx, which is capable of detoxifying peroxides. The activity of SOD did not change in CAPD patients. These results propose a possible role of free radicals with reduced antioxidant activity of GPx in CAPD patients and indicate that they could play some role in other pathological conditions such as atherogenesis and hemolysis.

Antioxidant enzymes--superoxide dismutase and glutathione peroxidase--in haemodialyzed patients

The biological effect of oxygen-reactive species controlled by antioxidant mechanisms are exerted on the basis of antioxidant enzymes and substrates. In this study, the activities of antioxidant enzymes-superoxide dismutase (SOD) and glutathione peroxidase (GPx)-were determined in the erythrocytes of patients on regular haemodialysis treatment. The SOD activity was significantly lower (1,810.38 +/- 609.85 vs. 2,347.13 +/- 502.51 U/g haemoglobin, p < 0.05, or 70.71 +/- 11.50 vs. 100.13 +/- 24.28 mU/10(6) erythrocytes, p < 0.0001), as was the GPx activity (18.80 +/- 4.22 vs. 23.26 +/- 3.61 U/g haemoglobin, p < 0.01), when compared with the control group. A positive correlation between GPx activity and number of haemodialysis sessions was found (p = 0.0038), but no correlation between SOD activity and number of HD sessions. An inpaired antioxidant enzyme defence system, here represented by SOD and GPx levels, can potentiate injury caused by free radicals in haemodialysis patients.

[The role of oxygen radicals in the pathogenesis of glomerulonephritis]

In the pathogenesis of glomerulonephritis, acute renal failure, pyelonephritis and other diseases of the kidneys oxygen radicals are involved. Some types of glomerulonephritis are characterized by infiltration of the glomeruli by neutrophils and monocytes which can form oxygen radicals (superoxide, hydrogen peroxide). The increased amount of cAMP in glomeruli can be due to oxygen radicals. Cyclic nucleotides modulate the inflammatory or immune response in glomerular disease and play a part in the action of local mediators of the inflammation. Oxygen radicals act as second messenger for the activation of cytokines via NF-kappaB transcription factor, they stimulate the formation of TNF-alpha, IL-1, IL-6 and influence the expression of monocyte-specific cytokines (CSF-1 and MCP-1). Radicals formed by the system myeloperoxidase--hydrogen peroxide--halogen derivatives activate proteolytic enzymes (proteinases) which break down collagen and other components of the extracellular matrix present in the basal membrane of glomeruli and in the mesangium. Oxygen radicals and proteinases can cause and amplify glomerular damage. Glucocorticoid administration leads to an increased activity of endogenous antioxidant enzymes in the glomerulus and reduced the of lipid peroxidation.

[The effect of pefloxacin on nephrotic syndrome in experimental adriamycin nephropathy]

BACKGROUND

Antiproteinuric effect of pefloxacine was demonstrated in a small group of patients with minimal change nephropathy (MCN) and focal and segmental glomerulosclerosis (FSGS). This finding was not, however, confirmed by other papers. Adriamycine nephropathy is an experimental model of nephrotic syndrome with morphological changes resembling MCN and/or FSGS in patients.

METHODS AND RESULTS

Nephrotic syndrome was induced in rats by the i.v. administration of adriamycine. One part of nephrotic animals was treated from the beginning of the 4th week by daily intraperitoneal application of pefloxacine. Administration of adriamycine led in experimental animals after 3 weeks to the development of full-blown nephrotic syndrome with further progression of proteinuria in the next 3 weeks (from 1.4 +/- 1.25 to 2.23 +/- 1.89 g of protein/mmol of urinary creatinine, p < 0.05). Proteinuria did not change in nephrotic rats treated by pefloxacine (from 1.04 +/- 0.97 to 1.26 +/- 1.11 g of protein/mmol of urinary creatinine, p = n.s.). The difference in proteinuria between both groups was also significant (0.83 +/- 0.73 vs. 0.23 +/- 0.67 g of protein/mmol of urinary creatinine, p < 0.05).

CONCLUSIONS

Pefloxacine was antiproteinuric in experimental adriamycine nephropathy. The mechanism of this effect remains unclear and deserves further studies concentrating on glomerular cytokine network and glomerular production of reactive oxygen species.

[Free radicals in the pathogenesis of selected diseases]

Free radicals are chemical substances which contain one or more unpaired electrons, which is the cause of their high reactivity with a series of biologically important substances such as fatty acids, DNA, RNA, amino acids. The source of radicals are immunological reactions and reactions in the endoplasmatic reticulum during detoxication of xenobiotics. Free radicals can act on the organism by a number of reactions, the most frequent on being lipid peroxidation when important toxic products are formed such as 4-hydroxy 2,3 trans-nonenal (4-HNE) and malondialdehyde. Direct assessment of free radicals due to their short life span is difficult in clinical practice. The majority of measurements is based on the assessment of substances which are formed by the reaction of free radicals in the organism. The most frequent method is assessment by means of thiobarbituric acid. Oxidative stress (the reaction produced by the action of free radicals) of tissues and cells is caused by the increased formation of free radicals and/or reduced capacity of antioxidant systems. Free radicals are involved in the process of ageing, cancerogenesis, inflammatory and degenerative diseases, atherogenesis, and play a part in the ischaemic and toxic damage of the organism. During evolution antioxidant defence mechanisms developed which under physiological conditions are sufficient to inactivate free radicals. Antioxidant systems can be divided into two groups--antioxidant enzymes (superoxide dismutase, glutathione peroxidase, catalase etc) and antioxidant substrates (tocopherols, carotenoids, ascorbic acid, glutathione, transferrin, ceruloplasmin etc).

Lipid peroxidation and superoxide dismutase activity in umbilical and maternal blood

Oxygenation of both mother and child tissues oscillate frequently during labour. We tested the lipid peroxidation caused by reactive oxygen species which are produced in consequence of tissue reoxygenation and the inactivation of these species by the maternal and newborn superoxide dismutase. Total malondialdehyde in concentrations (mean +/- SE) of 1.04 +/- 0.17, 1.57 +/- 0.22, 1.33 +/- 0.14 and 1.36 +/- 0.21 mumol/L was found in maternal plasma and red blood cells and newborn plasma and red blood cells, respectively, after uncomplicated deliveries and 4.93 +/- 1.34, 7.12 +/- 1.37, 4.77 +/- 1.29 and 7.37 +/- 1.51 mumol/L, respectively, after deliveries with clinical signs of foetal hypoxia. In newborns, erythrocyte superoxide dismutase activity reached only 82% of the maternal level (p < 0.05). The results indicate that the maternal and foetal antioxidant defence systems can be overloaded during deliveries with abnormal oxygenation, where increased lipid peroxidation occurred.

Activity of the antioxidant enzyme, glutathione peroxidase, on autosomal dominant polycystic kidney disease patients

Reactive oxygen species are generated physiologically in cells with a significant increase in certain pathological conditions, such as inflammation, cancer, aging, degenerative disease. If endogenous antioxidant systems, in our study represented by glutathione peroxidase, are exceeded by this oxidant flux, tissue injury may occur. Activity of glutathione peroxidase (GPx) was determined using Beutler's modified spectrophotometric assay in erythrocytes from autosomal dominant polycystic kidney disease patients. Activity of glutathione peroxidase was significantly (at p < 0.0001) lower there (17.75 +/- 3.69 U/g haemoglobin) compared to the control group (23.26 +/- .61 U/g Hb). Lower antioxidant enzyme defence system of ADPKD patients, here represented by GPx, can potentiate injury caused by free radicals and possibly play a role in the progression of autosomal dominant polycystic kidney disease.

The influence of chronic ethanol administration on adriamycin-induced nephrotic syndrome in rats

Alcoholic liver disease may be frequently complicated by mesangial proliferation with the deposition of IgA in glomeruli and glomerulosclerosis, but these glomerular lesions are usually mild and without greater impact on renal function. To evaluate the putative role of ethanol in glomerular pathology we studied the influence of chronic ethanol administration on the development of experimental adriamycin nephropathy in rats. Nephrotic syndrome was induced by a single i.v. dose of adriamycin (5 mg/kg body wt) both in rats given ethanol at a dose of 4 g/day for 3 months and control rats given standard chow. Further controls on both diets without adriamycin administration were also studied. Blood and urine were examined before and 3 and 6 weeks after adriamycin administration. All rats were killed and examined histologically 6 weeks after adriamycin administration. Ethanol fed nephrotic rats were more catabolic than control nephrotic rats (with higher free fatty acids, lower glycaemia, higher urea with similar creatinine) and had lower proteinuria (0.55 +/- 0.34 versus 5.79 +/- 3.15 g of protein/nmol of creatinine, P < 0.05), higher albuminaemia (5.41 +/- 2.62 versus 1.92 +/- 1.94 g/l, P < 0.01), lower plasma cholesterol (6.54 +/- 2.6 versus 10.57 +/- 2.92 mmol/l, P < 0.01) and triglycerides. The development of nephrotic syndrome and renal morphological changes after adriamycin administration in rats seemed to be ameliorated, or at least delayed by chronic ethanol feeding with much milder and focal glomerulosclerosis as compared with more severe and diffuse glomerulosclerosis in control nephrotic animals. The mechanism of this effect of chronic ethanol feeding remains to be elucidated.(ABSTRACT TRUNCATED AT 250 WORDS)

[The effect of chronic administration of ethanol on experimental adriamycin nephropathy]

BACKGROUND

Alcoholic liver disease may be in humans frequently complicated by mesangial proliferation and sclerosis. The influence of chronic ethanol administration on experimental nephrotic syndrome has not been, however, studied yet.

METHODS AND RESULTS

Experimental nephrotic syndrome was induced in rats by the i.v. administration of adriamycin in ethanol fed rats and in rats given common laboratory chow. Chronic administration of ethanol was in nephrotic rats accompanied by the exaggerated lipolysis (free fatty acids were in control nephrotic rats lower than in nephrotic ethylic rats 6 weeks after adriamycin administration: 914.8 + 96.8 mumol/l vs. 1186.3 + 178.7 mumol/l, p < 0.01) and increased proteocatabolism; the development of nephrotic syndrome was ameliorated, or at least delayed, however, in ethylic rats (control nephrotic rats had higher proteinuria than nephrotic ethylic rats 3 weeks after adriamycin administration: 5.79 + 3.15 vs. 0.55 + 0.34 g protein/mmol creatinine, p < 0.01). In autopsy, diffuse global glomerulosclerosis was found in control nephrotic rats with only mild focal and segmental changes in nephrotic ethylic rats.

CONCLUSIONS

Chronic ethanol administration ameliorated and/or delays the development of nephrotic syndrome in adriamycin nephropathy in rats. Mechanism of this effect of chronic ethanol feeding remains to be elucidated. Metabolic, immunosuppressive and renal haemodynamic effects of ethanol should be taken into consideration.