T. Jevtovic

Low Catalase Activity in Rats with Ureteral Ligation: Relation to Lipid Peroxidation

Progression of some renal diseases is characterized by generation of reactive oxygen metabolites that are also involved in the pathophysiology of obstructive nephropathy. Catalase activity and lipid peroxidation were investigated in rats with unilaterally (UUL) and bilaterally ligated ureters (BUL). Forty-eight hours after ligation, the animals were sacrificed, and enzyme activity as well as the malondialdehyde (MDA) concentration were measured in the plasma, kidneys and livers. The activity of catalase was significantly reduced in the plasma of the BUL rats and in the kidneys of both investigated groups. In the liver, catalase activity was decreased only in the BUL group. The MDA concentration in the plasma and kidneys of the BUL rats was significantly increased while in the liver it remained unchanged. These results suggest that lipid peroxidation in the induced uremic state could be responsible for catalase inactivation.

Protective Effects of Glutathione and Lipoic Acid against Cadmium- Induced Oxidative Stress in Rat's Kidney

Cadmium is a widespread, toxic industrial pollutant. The proximal tubule of the mammalian kidney is a major target of Cd-induced toxicity. We analyzed the effects of cadmium exposure on the model system of experimental animals, the thiobarbituric acid (TBA)-reactive substance (TBARS) level, and the activity of xanthine oxidase (XO) and catalase in kidney of rats, with and without glutathione and lipoic acid (LA). The experimental animals were classified into six groups, regarding cadmium, glutathione, and LA intake. The concentration of TBARSs in the homogenate was determined by spectrophotometric method according to Nabavi et al. The specific activity of XO was determined spectrophotometrically by the method of Aygul et al. Catalase activity in tissues was determined by spectrophotometric method according to Nabavi et al. The increased level of TBARS and the increased activity of XO in kidney tissue in cadmium poisoning are statistically significant compared to control (p < 0.001). Glutathione and LA applied along with cadmium lowered TBARS concentration and reduced XO activity (p < 0.001). Catalase activity in the kidney tissue was increased in the group, which was administered cadmium (p < 0.001). In conclusion, glutathione and LA, as physiological antioxidants applied with cadmium, have reduced the level of lipid peroxide and the activity of XO, and can be used as protectors in conditions of cadmium poisoning.

Effects of glucocorticoids on polyamine metabolism in liver and spleen of guinea pig during sensitization

Summary.Glucocorticoids are potent anti-inflammatory and immunosuppressive agents. As endogenous inhibitors of cytokine synthesis, glucocorticoids suppress immune activation and uncontrolled overproduction of cytokines, preventing tissue injury. Also, polyamine spermine is endogenous inhibitor of cytokine production (inhibiting IL-1, IL-6 and TNF synthesis). The idea of our work was to examine dexamethasone effects on the metabolism of polyamines, spermine, spermidine and putrescine and polyamine oxidase activity in liver and spleen during sensitization of guinea pigs. Sensitization was done by application of bovine serum albumin with addition of complete Freund’s adjuvant. Our results indicate that polyamine amounts and polyamine oxidase activity increase during immunogenesis in liver and spleen. Dexamethasone application to sensitized and unsensitized guinea pigs causes depletion of polyamines in liver and spleen. Dexamethasone decreases polyamine oxidase activity in liver and spleen of sensitized guinea pigs, increasing at the same time PAO activity in tissues of unsensitized animals.

ANTIOXIDANTS MODULATE ADENOSINE METABOLISM IN RAT MESANGIAL CELLS CULTURED UNDER HIGH GLUCOSE CONDITIONS

Glomerular mesangial cells play a major role in glomerular hemodynamics, considered also as antigen-presenting cells participating in immune response. Mesangial dysfunction and proliferation are typical lesions of diabetic glomerulopathy. Adenosine, a local hormone, produced by mesangial cells is a metabolic regulator of renal blood flow, capable of decreasing glomerular filtration rate (GFR), exerting immunosuppressive, antiproliferative and anti-inflammatory properties. Since it was well established that antioxidants confer protection against increased oxidative stress that occurs in diabetes, the effect of captopril, reduced glutathione and melatonin on adenosine metabolism was investigated. Glomerular mesangial cells obtained from collagenase treated glomeruli, isolated from renal cortex of Sprague-Dowley rats, were grown under high glucose conditions (30 mmol/L) as a model of diabetic microenvironment. The activity of adenosine metabolizing enzymes: 5′-nucleotidease (5′-NU) responsible for its production and adenosine deaminase (ADA)—responsible for its degradation were investigated. Hyperglycemic conditions led to decreased adenosine production via 5′-NU and decreased removal via ADA. Captopril, given in therapeutic concentration induced enzyme activities in normoglycemic conditions and restored hyperglycemia—induced decrease. In order to investigate if the presence of SH groups may be responsible for this improvement, the cells were exposed to reduced glutathione, and it exerted almost equal effect, given in physiological and higher concentrations. Melatonin increased 5′-NU activity only in physiological glucose conditions. Presented results confirm potential renoprotective effect of SH-group containing antioxidant supplementation during diabetes in restoring adenosine metabolism.

DOES CAPTOPRIL CHANGE OXIDATIVE STRESS IN PUROMYCIN AMINONUCLEOSIDE NEPHROPATHY

Puromycin aminonucleoside (PAN) nephropathy in rats has been induced by the intraperitoneal injections of PAN. One group of animals which received PAN has been treated simultaneously with captopril (angiotensine converting enzyme-ACE-inhibitor) with the aim to test whether continuing treatment with captopril along with PAN injections would be able to modulate the toxic effects of PAN. The third group of rats was given only captopril. Morphological changes in the kidney were evaluated by scanning electron microscopy that showed the loss of podocyte foot processes in the kidney of PAN treated animals but also in the kidney of captopril treated ones as well as in the animals treated with both drugs simultaneously. Reduced glutathione content, catalase, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), xanthine oxidase activities as well as lipid peroxides were investigated in rat blood and kidney. Captopril given alone produced a significant decrease of plasma lipid peroxides, but it did not show any significant effect on investigated antioxidative factor levels neither in blood nor in the kidney. PAN given alone produced a significant depletion of plasma lipid peroxides, kidney catalase and erythrocyte GSH-Px activity as well as a significant increase of plasma catalase and erythrocyte SOD activity. Treatment of animals with both drugs simultaneously resulted in a significant increase of erythrocyte SOD activity and a significant decrease of plasma lipid peroxides, erythrocyte GSH-Px and kidney SOD activities. Kidney xanthine oxidase activity showed a significant increase in both PAN and PAN plus captopril treated animals in comparison with the values of captopril treated rats. These data suggest that PAN changes the antioxidative factor pattern in rat blood and kidney. Contrary to our expectations that captopril may protect the toxic effects of PAN it only to a certain extent modifies these effects showing protective effect only on tissue catalase activity.

Possible impact of plasma RNase activity on immune dysfunction in juvenile diabetes mellitus

Aim:  The ribonuclease (RNase) family represents important enzymes used widely in biomedical and biotechnological applications, as well as for diagnostic and therapeutic purposes. This study was undertaken to test the possibility that plasma alkaline RNase (free or inhibitory bound) determination may be useful in studying the dysregulation of nucleic acid and oligonucleotide metabolism as a possible pathogenetic mechanism in development of immune dysfunction in juvenile diabetes mellitus.

Protective effect of interferon-? on the DNA- and RNA-degrading pathway in anti-Fas-antibody induced apoptosis

Aim:  Fas membrane‐associated polypeptide antigen is a receptor molecule responsible for apoptosis‐mediated signals. In animal models of acute viral hepatitis, apoptosis of hepatocytes is mediated by Fas‐death receptors; therefore, the aim of this study was to evaluate the effect of interferon (IFN)‐α on apoptotic markers and nuclease activity against different coding and non‐coding single and double stranded RNAs during Fas‐induced liver apoptosis.

Short communication: Effect of commercial or depurinized milk diet on plasma advanced oxidation protein products, cardiovascular markers, and bone marrow CD34+ stem cell potential in rat experimental hyperuricemia

Cardiovascular repair and myocardial contractility may be improved by migration of bone marrow stem cells (BMSC) and their delivery to the site of injury, a process known as BMSC homing. The aim of our study was to examine the dietary effect of a newly patented depurinized milk (DP) that is almost free of uric acid and purine and pyrimidine compounds compared with a standard commercial 1.5% fat UHT milk diet or allopurinol therapy in rat experimental hyperuricemia. Bone marrow stem cell potential (BMCD34(+), CD34-postive bone marrow cells), plasma oxidative stress parameters [advanced oxidation protein products, AOPP) and thiobarbituric acid reactive substances (TBARS)], myocardial damage markers [creatine phosphokinase (CPK), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH)], plasma cholesterol, and high-density lipoprotein cholesterol were investigated. The DP milk diet significantly increased the number of BMCD34(+) stem cells compared with commercial UHT milk. Allopurinol given alone also increased the number of BMCD34(+). Hyperuricemia caused a significant increase in all plasma enzyme markers for myocardial damage (CPK, LDH, and AST). A cardioprotective effect was achieved with allopurinol but almost equally with DP milk and more than with commercial milk. Regarding plasma AOPP, TBARS, and cholesterol levels, the most effective treatment was DP milk. In conclusion, the protective role of a milk diet on cardiovascular function may be enhanced through the new depurinized milk diet, which may improve cardiovascular system function via increased bone marrow stem cell regenerative potential, decreased plasma oxidative stress parameters, and decreased levels of myocardial damage markers and cholesterol. New dairy technology strategies focused on eliminating harmful milk compounds should be completely nontoxic. Novel milk products should be tested for their ability to improve tissue repair and function.

Vitamin Β12 and Folic Acid Effects on Polyamine Metabolism in Rat Liver

Abstract Polyamines, spennine, spermidine and putrescinc, small aliphatic nitrous bases, are normal constituents of microbial, plant and animal cells, where they fulfill an array of physiological roles. Metabolism of polyamines is associated with growth and differentiation of mammalian cells, spermine related to RNA and spermidine to DNA metabolism. Methyl-cobalamin, the coenzyme of methionine synthetase, catalyses the recycling of homocysteine to methionine using 5-methyltctrahydrofolate. By acceleration of methionine biosynthesis these vitamins may influence spermidine and spermine synthesis. Liver tissue is rich in polyamines and it is the place of vitamin B12 and folic acid deposition. Polyamine oxidase (PAO, EC 1.5.3) and diamino oxidase (DAO, EC 1.4.3.6) participate in the process of degradation and interconversion of spermine, spermidine and putrescinc. The idea of our work was to examine the effccts of cobalamin and folic acid on the polyamine metabolism. We have examined the amount of spermine, spermidine and putrescine in liver tissue. At the same time we have examined the activities of PAO and DAO, the catabolic enzymes of polyamine metabolism. Our result suggest that the supplementation of experimental animals with vitamin B12 alone or together with folic acid augmentais spermidine and spermine levels in rat liver, at the same time the amount of putrescine does not change. The application of vitamin cobalamin to experimental animals alone increases PAO; the supplementation of experimental animals with vitamin Β12 together with folic acid causes opposite effect - the decrease of PAO activity. DAO activity significantly decreases under the influence of cobalamin and also with cobalamin and folic acid in combination. Our experimental results indicate the importance of cobalamin and folic acid in polyamine metabolism.

Circulating nucleic acids in type 1 diabetes may modulate the thymocyte turnover rate

The autoimmunity of type 1 diabetes is associated with T-cell hyperactivity. Current study was designed to examine the effect of circulating ribonucleic acids (RNAs), isolated from type 1 diabetic patients on proliferative, apoptotic and inflammatory potential of rat thymocytes. Rat thymocytes were assayed for proliferating nuclear cell antigen (PCNA), Bcl-2, Bax and NF-κB level, using the flow cytometric and fluorometric assays. Cells were allocated into groups, treated with RNAs purified from plasma of juvenile diabetics, adult type 1 diabetic patients, control healthy children, healthy adult persons, nucleic acids and polynucleotide standards (RNA, polyC, PolyA, PolyIC, and CpG). The upregulation of PCNA and Bcl-2 protein and downregulation of Bax protein and NF-κB was shown when the thymocytes where incubated with RNA purified from plasma of juvenile type 1 diabetic patients. The dysregulation of inflammatory cascade and central tolerance may be a defect in autoimmune diseases related to innate immunity leading to corresponding alteration in adaptive immune response.