Tomáš Zima

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.

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.

Receptor for advanced glycation end products (RAGE)--soluble form (sRAGE) and gene polymorphisms in patients with breast cancer.

Receptor for advanced glycation end products (RAGE) may be involved in the pathogenesis of the cancer progression and metastasis. Pathological effects mediated via RAGE are physiologically inhibited by soluble RAGE (sRAGE), so the higher sRAGE levels may confer the patients with cancer with better outcome. The aim was to study sRAGE and RAGE gene polymorphisms in patients with breast cancer. The authors studied sRAGE and RAGE polymorphisms in 120 patients with breast cancer (subdivided based on the clinical stage, histologic grading, expression of hormonal and Her2/neu receptors) and in 92 healthy controls. Despite higher serum concentrations of AGEs, serum concentrations of sRAGE were lower in patients with breast cancer compared to healthy controls (1581 ± 777 versus 1803 ± 632 ng/mL, p < 0.05). Serum levels of sRAGE were higher in patients with advanced breast cancer (stage III), lower grade and positive estrogen receptors, and intermediate positivity of Her2/neu receptors and were also influenced genetically (Gly82Ser and 2184 AG polymorphisms of the RAGE gene). Decreased sRAGE levels in patients with breast cancer may contribute to the progression of the disease. Patients with better outcome (low grade and positive estrogen receptors) have higher sRAGE levels. Progression of the disease, may, however, increase sRAGE levels, possibly as a compensatory mechanism to counteract further progression.

Randomized prospective comparative study of ursodeoxycholic acid and S-adenosyl-L-methionine in the treatment of intrahepatic cholestasis of pregnancy.

Abstract Aim: To compare the efficacy of the ursodeoxycholic acid (UDCA) and S-adenosyl-L-methionine (SAMe) monotherapy with their combined effect on intrahepatic cholestasis of pregnancy (ICP). Patients and methods: We studied singleton pregnancies at <36 weeks with a moderate or severe form of ICP between January 1999 and March 2004. Patients were randomized to either oral UDCA 3×250 mg daily or 500 mg SAMe twice daily in slow running infusion for twelve days followed by oral administration of 500 mg twice daily until delivery. Intensive hematological, biochemical and fetal monitoring were carried out. Results: Of the 78 women enrolled, 25 received SAMe monotherapy, 26 received UDCA, and 27 received combined therapy. Groups were initially comparable in terms of gestational age, duration of therapy, parity and biochemical characteristics. All therapies improved the pruritus. The combined therapy and the monotherapy with UDCA (later) led to improving of the serum concentrations of bile acids and transaminases compared with SAMe monotherapy (P<0.01). Combined therapy led to a faster decrease of serum concentrations of bile acids and transaminases compared with UDCA monotherapy (borderline significance). Gestational ages were similar in all groups. No adverse effects were noted on the fetuses or neonates with either therapy. Conclusions: UDCA is an effective drug in the treatment of ICP, and combined with SAMe, has probably a synergistic effect on biochemical parameters. This mode of treatment seems more effective but the effect of the successful treatment on the fetus is unclear. Therefore, the ante- and intrapartum monitoring of the fetus should be part of the management of severe forms of ICP. The project is supported by IGA MZ CR (No. NH/7376-3)

Depression, traumatic stress and interleukin-6

BACKGROUND Recent evidence indicates that various types of interactions between nervous and immune system are important in pathogenesis of depression. These findings show that a significant role in developing depression play pro-inflammatory cytokines that may mediate its psychological, and neurobiological manifestations. Great importance among these cytokine molecules plays interleukin-6 (IL-6). There is growing evidence that this inflammatory process related to depression may be influenced by psychological stress as well as organic inflammatory conditions. These findings suggest that specific influences related to traumatic stress and dissociation could be found in close relationship to increased level of cytokine IL-6. METHODS In the present study we have performed psychometric measurement of depression (BDI-II), traumatic stress symptoms (TSC-40) and dissociation (DES, SDQ-20), and immunochemical measure of serum IL-6 in 40 inpatients with unipolar depression (mean age 42.3+/-6.8). RESULTS The results show that IL-6 is significantly correlated to BDI-II (Spearman R=0.47, p<0.01), TSC-40 (Spearman R=0.32, p<0.05), SDQ-20 (Spearman R=0.34, p<0.05) but not to DES (Spearman R=0.25, p=0.11). CONCLUSION The findings of the present study indicate that increased level of IL-6 in depression could be directly related to symptoms of traumatic stress and somatoform dissociation.

Trace Elements in Hemodialysis and Continuous Ambulatory Peritoneal Dialysis Patients

Alterations in blood and tissue concentrations of trace elements in patients with chronic renal failure have been extensively investigated. Selenium, zinc and copper are elements which play an important role in biological systems as components of proteins, enzymes and antioxidants. The concentrations of selenium, zinc and copper were determined in the plasma, erythrocytes and whole blood of patients on regular hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) treatment using the method of inductively coupled plasma mass spectrometry (ICP-MS). Analysis of isotopes 77Se, 66Zn and 65Cu was performed. Methodology presents the major limitation to valid studies on trace element levels in biological materials. One of the widely used contemporary techniques is ICP-MS. It is the most sensitive one and has a high dynamic range. The selenium concentration in the studied compartments (plasma 46.1 ± 3.0 vs. 78.0 ± 3.4 μg/l, p < 0.001; erythrocytes 90.4 ± 6.5 vs. 134.2 ± 7.6 μg/l, p < 0.01; whole blood 67.3 ± 3.1 vs. 106.4 ± 3.4 μg/l, p < 0.001) was significantly lower in HD patients compared to healthy controls. The same result was observed in plasma (63.2 ± 5.8 vs. 78.0 ± 3.4 μg/l, p < 0.05) and whole blood (82.7 ± 7.4 vs. 106.4 ± 3.4 μg/l, p < 0.01) from CAPD patients, but the selenium level of erythrocytes in CAPD patients was the same as in the control group (126.0 ± 8.8 vs. 134.2 ± 7.6 μg/l). The cooper content of erythrocytes was lower in HD patients than in controls (0.55 ± 0.02 vs. 0.66 ± 0.01 mg/l, p < 0.01) and CAPD groups (0.55 ± 0.02 vs. 0.68 ± 0.02 mg/l, p < 0.001). There were no differences in copper content in plasma (HD 1.02 ± 0.06; CAPD 1.11 ± 0.09; controls 1.02 ± 0.05 mg/l) and whole blood (HD 0.87 ± 0.04; CAPD 0.90 ± 0.05; controls 0.85 ± 0.02 mg/l) in HD and CAPD patients and healthy controls. The zinc concentration was increased in the whole blood of CAPD patients (6.68 ± 0.36 vs. 5.52 ± 0.11 mg/l, p < 0.001) and erythrocytes of HD (12.30 ± 0.23 vs. 10.11 ± 0.42 mg/l, p < 0.001), and CAPD groups (13.71 ± 0.56 vs. 10.11 ± 0.42 mg/l, p < 0.001) compared to controls. However, the plasma zinc concentration was lower in HD patients compared to blood donors (0.69 ± 0.03 vs. 0.92 ± 0.03 mg/l, p < 0.001) and CAPD patients (0.69 ± 0.03 vs. 0.95 ± 0.04 mg/l, p < 0.001). We did not find a significant increase in trace elements in whole blood after HD. These results suggest differences between plasma, erythrocytes and whole blood concentrations of the studied trace elements. The levels of trace elements are altered by HD and CAPD. A modern precise method with high accuracy, ICP-MS, which was used in our study, eliminated analytical errors and possible interferences.

Advanced Glycation End Products in Clinical Nephrology

As a result of oxidative and carbonyl stress, advanced glycation end products (AGEs) are involved in the pathogenesis of severe and frequent diseases and their fatal vascular/cardiovascular complications, i.e. diabetes mellitus and its complications (nephropathy, angiopathy, neuropathy and retinopathy, renal failure and uremic and dialysis-associated complications), atherosclerosis and dialysis-related amyloidosis, neurodegenerative diseases, and rheumatoid arthritis. They are formed via non-enzymatic glycation which is specifically enhanced through the presence of oxidative and carbonyl stress, and their ability to form glycoxidation products in peptide and protein structures finally modulating or inducing biological reactivity. Food can be another source of AGEs; however, high serum AGEs in hemodialysis patients might reflect nutritional status better. Several methods of renal replacement therapy have been studied in connection with the AGE removal, but unfortunately the possibilities are still unsatisfactory even if high flux dialysis, hemofiltration, or hemodiafiltration give better results than conventional low flux dialysis. AGEs are currently being studied in the patients on peritoneal dialysis as their precursors can be formed in the dialysis fluid. AGEs can cause damage to the peritoneum and so a loss of ultrafiltration capacity. Many compounds give promising results in AGE inhibition (inhibition of formation of AGEs, inhibition of their action or degradation of AGEs), are tested for these properties, and eventually undergo clinical studies (e.g. aminoguanidine, OPB-9195, pyridoxamine, antioxidants, N-phenacylthiazolium bromide, antihypertensive drugs, angiotensin-converting enzyme inhibitors and angiotensin II receptor-1 antagonists).

Oxidative stress and inflammation in pregnancy

Pregnancy is a period when increased oxidative stress can be expected. We have focused especially on oxidative stress and inflammation in the period of pregnancy, when prenatal screening is usually performed. We determined advanced oxidation protein products (AOPPs), C‐reactive protein (CRP) and anticardiolipin antibodies (ACA) IgG and IgM levels in the serum of 86 pregnant women in the 1st trimester and 102 pregnant women in the 2nd trimester. AOPP levels in the maternal serum of pregnant women were significantly higher in the 1st and 2nd trimesters than they were in that of non‐pregnant women (p<0.0001, p<0.001, respectively). Maternal serum CRP levels, too, were increased compared with those in non‐pregnant women (1st and 2nd trimester versus non‐pregnant women p<0.05, p<0.005, respectively). Just as with AOPPs and CRP, the ACA IgG levels in pregnant women were significantly higher in both trimesters than they were in non‐pregnant women (1st and 2nd trimesters versus non‐pregnant women p<0.05, p<0.001, respectively). Maternal serum CRP levels correlated positively with AOPPs in the 2nd trimester (r = 0.504, p<0.05). The increased levels of AOPPs, CRP and ACA IgG in the 1st and 2nd trimesters may reflect a maternal response to inflammatory and oxidative stress in pregnant women.

Influence of Plasma Exchange on Serum Levels of Cytokines and Adhesion Molecules in ANCA-Positive Renal Vasculitis

Background: Increased serum levels of proinflammatory cytokines may contribute to the organ damage in active antineutrophil cytoplasmic antigen (ANCA)-positive renal vasculitis. Plasma exchange (PE) may influence the activity of vasculitis not only by removing pathogenic autoantibodies, but also by lowering the serum levels of circulating cytokines. Methods: Serum levels of IL-1β, IL-1ra, IL-6, IL-8, ICAM-1 and VCAM-1 were measured using ELISA in 10 patients with active ANCA-positive renal vasculitis (5 patients with Wegener’s granulomatosis, WG, and 5 patients with microscopic polyangiitis, MPA) during the course of therapeutic PE. Cytokines and adhesion molecules were measured in samples of serum obtained at the beginning and at the end of the 1st, 3rd and 5th PE and in samples of filtrate obtained during the same PE. Results: In comparison with controls, patients with ANCA had higher serum levels of IL-1ra, IL-8, ICAM-1 and VCAM-1 before the 1st PE. Serum levels of IL-6, IL-8, ICAM-1 and VCAM-1 were increased in patients with MPA, and the serum levels of all the cytokines and adhesion molecules measured in patients with WG were increased. At the end of the PE course there were decreases in the serum levels of IL-1ra and VCAM-1 in ANCA patients and IL-1ra and ICAM-1 in WG patients. Single PE in ANCA patients led only to a decrease in serum levels of ICAM-1 and VCAM-1. On the other hand, there was no change in serum levels of IL-1β and IL-8, and the serum levels of IL-1ra and IL-6 even increased at the end of a single PE, in spite of high levels of all cytokines and adhesion molecules in the plasma filtrate. Conclusion: Serum levels of soluble adhesion molecules decrease after PE, but serum levels of proinflammatory cytokines are not reduced even by a PE course. Removal of these substances by PE is obviously counteracted by their increased production, possibly further stimulated by the contact of blood with the synthetic membrane. The insufficient influence of PE on the elimination of proinflammatory cytokines may partially explain its limited effect in some patients with ANCA-positive renal vasculitis.

Human Galectins Induce Conversion of Dermal Fibroblasts into Myofibroblasts and Production of Extracellular Matrix: Potential Application in Tissue Engineering and Wound Repair

Members of the galectin family of endogenous lectins are potent adhesion/growth-regulatory effectors. Their multifunctionality opens possibilities for their use in bioapplications. We studied whether human galectins induce the conversion of human dermal fibroblasts into myofibroblasts (MFBs) and the production of a bioactive extracellular matrix scaffold is suitable for cell culture. Testing a panel of galectins of all three subgroups, including natural and engineered variants, we detected activity for the proto-type galectin-1 and galectin-7, the chimera-type galectin-3 and the tandem-repeat-type galectin-4. The activity of galectin-1 required the integrity of the carbohydrate recognition domain. It was independent of the presence of TGF-β1, but it yielded an additive effect. The resulting MFBs, relevant, for example, for tumor progression, generated a matrix scaffold rich in fibronectin and galectin-1 that supported keratinocyte culture without feeder cells. Of note, keratinocytes cultured on this substratum presented a stem-like cell phenotype with small size and keratin-19 expression. In vivo in rats, galectin-1 had a positive effect on skin wound closure 21 days after surgery. In conclusion, we describe the differential potential of certain human galectins to induce the conversion of dermal fibroblasts into MFBs and the generation of a bioactive cell culture substratum.