Asymmetric dimethylarginine and the effect of folate substitution in children with familial hypercholesterolemia and diabetes mellitus type 1.

A recently discussed cardiovascular risk factor, asymmetric dimethylarginine (ADMA), is known to act as an endogenous inhibitor of endothelial nitric oxide synthase. The aim of this study was to establish 1) the relationship between ADMA and ultrasonographically or biochemically determined endothelial dysfunction in children, and 2) the effect of folate supplementation on these parameters. The study cohort included 32 children with familial hypercholesterolemia (FH), 30 with diabetes mellitus type 1 (DM1) and 30 age-matched healthy children as the control group. Furthermore, twenty-eight randomly selected FH and DM1 children were re-examined after 3-months supplementation with folic acid. Baseline levels of ADMA and oxidized low density lipoproteins (oxLDL) were significantly higher in FH group than in DM1 and healthy children. Children in DM1 group had significantly lower concentration of homocysteine, but ADMA levels were normal. Folic acid supplementation significantly lowered homocysteine and hsCRP levels in both FH and DM1 group; however, ADMA and oxLDL concentrations remained unaltered. In conclusion, ADMA and oxLDL appear to be associated with endothelial dysfunction in children with FH. Administration of folic acid did not influence these markers in both FH and DM1 children.

The influence of folate and antioxidants on homocysteine levels and oxidative stress in patients with hyperlipidemia and hyperhomocysteinemia.

The aim of this study was to observe the effect of folate and antioxidants alone on homocysteine levels and oxidative stress markers, and to evaluate whether their co-administration promotes their effects. One hundred patients with hyperhomocysteinemia were randomized into four equal groups, which were then treated with folate, antioxidants or folate plus antioxidants for 2 months; group IV was a control group. Serum homocysteine, folate and oxidative stress markers were measured before the study, at the end of folate and/or antioxidants administration and 3 months later. Folate caused a significant decrease in homocysteine concentration. Antioxidants did not influence homocysteine concentration, but they improved the antioxidative defense (plasma antioxidant capacity and intraerythrocyte glutathione were increased) and partially prevented lipid peroxidation (malondialdehyde level was slightly decreased). Supplementation with folate had a similar effect on intracellular glutathione and plasma malondialdehyde. Simultaneous administration of folate and antioxidants did not show any additive effect with the exception of a slower decrease of folate concentration after its supplementation had been discontinued. Folate may be considered as an effective antioxidant in patients with hyperhomocysteinemia; this can be a result of decreased production of free radicals due to a reduced level of homocysteine. Its antioxidative effect cannot be promoted by co-administration of antioxidants.

[The significance of free radicals and antioxidants due to the load induced by sport activity]. / Význam volných radikálu a antioxidantu sportovní záteze.

Sport performance is followed by a high production of free radicals. The main reasons are reperfusion after the previous imbalance between the increased need of the organism and the ability of blood supply by oxygen, increased production of ATP, decomposition of the cells particularly white blood cells, oxidation of the purin basis from DNA, stress, output of epinephrine release of free iron, increased temperature in the muscle and its inflammation, and the reception of free radicals from external environment. Peroxidation of lipids, proteins, DNA and other compounds follows the previous biochemical steps. Antioxidants are consumed by free radicals, antioxidative enzymes are released into blood plasma, intracellular calcium is increased, the production of nitric oxide rises, the levels of hydrogen peroxide and hypochlorous acid increase. These penetrate through the membranes and oxidatively damage the tissues. Training improves the ability of the organism to balance the increased load of free radicals. The damage can be lowered by the application of a mixture of antioxidants, the most important are vitamin C, A, E, glutathione, selenium, carnosine, eventually bioflavonoids and ginkgo biloba. The lack of antioxidants can significantly diminish the sport performance and therefore the supplementation with antioxidants is for top sportsmen but also for aged people advisable.

Can ischemia-reperfusion syndrome in transplanted kidneys procured from non-heart-beating donors be influenced by adding selenium into the reperfusion solution? An experimental study.

Ischemia-reperfusion syndrome significantly influences the function of a kidney transplanted from a non-heart-beating donor (NHBD). An animal model of NHBD was used to monitor the influence of the exogenous addition of selenium in the perfusion solution (HTK, Custodiol) on the generation of free oxygen radicals between 0 and 120 minutes after transplantation of the NHBD organ. During this interval, the malondialdehyde concentration, an indicator of free oxygen radicals in the venous blood of the transplanted kidney, significantly decreased. The augmentation of the anti-oxidant capacity of the preservation solution might represent a possible improvement in the function of kidneys transplanted from NHBDs.

[Chromium as an essential element]. / Chrom jako biogenní prvek.

Chromium was known for many years to be an element causing allergic reactions and having neurotoxic and carcinogenic effects. These effects can be observed especially in the case of hexavalent chromium. Only a little more than four decades ago trivalent chromium has been known as an essential element with relation to glycide and lipid metabolism. And only during several last years this chromium function has been revealed on a molecular level. After absorption in the gastrointestinal tract, chromium is most likely transported to cells bound to the plasma protein transferrin. Insulin initiates chromium transport into the cells where it is bound to the oligopeptide apochromodulin. This oligopeptide combined with four chromium(III) atoms forms chromodulin, which is important for amplifying the insulin signalling effect. After binding to insulin-activated receptor, chromodulin increases tyrosine kinase activity by one order. This enzyme forms a part of intracellular portion of insulin receptor. Chromium supplementation in people with chromium deficiency can improve glucose tolerance and some lipid metabolism parameters. The supplementation is indicated in persons with impaired glucose tolerance both in preclinical and manifested stadium of type 2 diabetes mellitus where increased lost of chromium in urine was documented. In these patients, chromium deficiency can participate in insulin resistance and hyperlipidaemia. Chromium is usually applied in the form of organic compounds: yeast extract or chromium(III) picolinate. Cr(III) picolinate can be reduced to compounds of Cr(II) in the cells which can then produce free hydroxyl radical in the so called Fenton reaction.

Can the ischemia-reperfusion syndrome in transplanted kidneys procured from non-heart-beating donors be influenced by adding selenium into the reperfusion solution? An experimental study.

The ischemic-reperfusion syndrome significantly influences the function of a kidney transplanted from a non-heart-beating donor (NHBD). The animal model of a NHBD was used to monitor the influence of exogenous addition of selenium into the reperfusion solution (HTK, Custodiol) with respect to the formation of free oxygen radicals at 0 to 120 minutes after the NHBD transplantation. This maneuvers produced a statistically significant decrease in malondialdehyde concentration, an indicator of free oxygen radicals in the venous blood of the transplanted kidney. The augmentation of the antioxidative capacity of the preservation solution might be a possible route to improve the function of kidneys transplanted from NHBDs.

Effect of L-carnitine supplementation in hemodialysis patients.

BACKGROUND/AIM: L-Carnitine is important in beta-oxidation of fatty acids. A lack of carnitine in hemodialysis patients is caused by insufficient carnitine synthesis and especially by its loss during dialysis. The aim of our study was to test the influence of carnitine supplementation on plasma lipids, red blood cell count, and metabolism of free radicals. METHODS: Twelve regularly dialyzed patients (average age 55.5 years, average dialysis treatment period 22.5 months) were given 15 mg/kg L-carnitine intravenously three times weekly (after each hemodialysis session) for 6 months. Laboratory markers of oxidative stress, lipid metabolism, and red blood cell count were measured before the supplementation and then controlled during two 3-month intervals. Nine patients were retested 3 months after the supplementation had ended. RESULTS: All supplemented patients showed increased plasma free carnitine in comparison with the pretreatment values (113.3 +/- 11.2 vs. 62.3 +/- 16.7 micromol/l, p < 0.001). The proportion of decreased L-carnitine values after hemodialysis was reduced from 79 to 22%. Plasma total cholesterol (4.66 +/- 0.30 mmol/l after treatment vs. 5.65 +/- 1.53 mmol/l before treatment, p < 0.05) and LDL cholesterol (1.74 +/- 0.86 vs. 2.81 +/- 1.43 mmol/l, p < 0.05) decreased. The albumin concentration significantly increased from 34.8 +/- 7.3 to 46.0 +/-5.4 g/l (p < 0.05). Intraerythrocyte reduced glutathione increased from 1.65 +/- 0.25 to 2.23 +/- 0.16 mmol/l (p < 0.001), and the plasma antioxidant capacity increased from 1.65 +/- 0.09 to 2.06 +/- 0.17 mmol/l (p < 0.001). At the same time, plasma malondialdehyde decreased from 4.18 +/- 0.72 to 3.07 +/- 0.35 micromol/l (p < 0.001). The erythropoietin dose could be reduced from an average value of 5,500 to 3,500 U/week. No significant changes in the above-mentioned parameters were observed in a control group of dialyzed patients without L-carnitine supplementation. CONCLUSION: Regular carnitine supplementation of hemodialysis patients can improve their lipid metabolism, protein nutrition, red blood cell count, and antioxidant status.

Does exogenous melatonin influence the free radicals metabolism and pain sensation in rat?

Melatonin has been shown to play a role in antioxidative defence. We therefore studied its effect on oxidative damage to the rat cerebral cortex evoked by painful stimulation and immobilization-induced stress. Moreover, the effect of melatonin on chronic pain perception was examined. Rats were injected with either a high dose of melatonin (100 mg/kg i.p.) or a vehicle for five days and were subjected to painful stimulation or immobilization stress 30 min after the treatment. To determine the degree of oxidative stress, the levels of free radicals, thiobarbituric acid reactive substances (TBARS) as indicators of lipid peroxidation and glutathione peroxidase (GSHPx) were estimated in somatosensory cortex. Pain perception was measured by the tail-flick and plantar test. Melatonin reduced the level of TBARS previously increased by painful stimulation. Melatonin also exhibited a slight analgesic effect in those animals exposed to painful stimulation but its role in free radical scavenging did not contribute to this effect.

[Effect of antioxidant therapy on indicators of free radical activity in workers at risk of lead exposure]. / Ovlivnení ukazatelu pusobení volných radikálu u pracovníku v riziku olova antioxidacní lécbou.

The authors administered to 36 workers exposed to lead, for four weeks the preparation Prolong which contains vitamin C, vitamin E, beta-carotene, selenium, zinc and chromium and investigated the effect on indicators of free radicals. A statistically significant increase of the following occurred: superoxide dismutase (p < 0.001), glutathione peroxidase (p < 0.01), an increase of the total antioxidant capacity (p < 0.01) and an increase of uricaemia (p < 0.05). Based on these results the authors consider supplementation with antioxidants indicated in workers exposed to lead.

[Antioxidative properties of ascorbic acid]. / Antioxidacní vlastnosti kyseliny askorbové.

Vitamin C (ascorbic acid) is an important hydrophilic compound with antioxidative effect. In the introduction the authors describe possible consequences of loss of vitamin C synthetic ability in an evolutionary ancestor of Anthropoidea. Metabolism of this vitamin is described briefly along with possibilities of its supplementation and determination in biological fluids. Highest attention is paid to metabolic effects of vitamin C, respectively to changes which can be observed after its deprivation, or after the supplementation with this vitamin. Protective effect of vitamin C against lipoperoxidation, its role in modulation of immunity and tumorigenesis are described. Many effects of vitamin C can be explained by its antioxidative activity. The authors show that under concrete conditions, administration of vitamin C can be accompanied by a prooxidative effect. Since vitamin C works in cooperation with other antioxidants, its administration in diseases which are followed by oxidative stress is move effective when used in combined preparations.

[Free radicals and extracorporeal renal replacement therapy]. / Volné radikály a mimotelní náhrada funkce ledvin.

Free radicals (FR), highly reactive substances with an unpaired electron in the outer orbital attack lipids, proteins and nucleic acids and alter the structure and function of these macromolecules. Against the negative effects of FR during evolution various defense mechanisms developed described comprehensively as antioxidant defense. Under physiological conditions in the organism equilibrium is established between free radical production and antioxidant defense factors. Extracorporeal renal replacement mechanisms can interfere in a negative way with this equilibrium. They provoke the formation of FR and at the same time they weaken the antioxidant defense e.g. by elimination of substances with antioxidant properties. Impairement of the equilibrium between FR production and antioxidant mechanisms to the disadvantage of antioxidant defense in patients with chronic renal failure was proved and is described as oxidative stress. Oxidative stress threatens dialyzed patients with serious clinical complications e.g. accelerated atherosclerosis, amyloidosis, haemolysis and the development of a state of chronic inflammation. Reduction of oxidative stress can be achieved by reducing FR production by using biocompatible dialyzation membranes, proper correction of acid-base disorders, by preventing an iron overload of the organism. The second approach is to foster the antioxidant defense by supplementation with antioxidants. Final recommendations as regards selection of the optimal dialyzation membrane, type of extracorporeal renal replacement and the amount and composition of antioxidant supplements have not yet been established and the problem is the subject of intense research.

[Indicators of effects of free radicals in workers at risk of lead exposure]. / Ukazatelé pusobení volných radikálu u pracovníku v riziku olova.

The authors examined indicators of the action of free radicals in 40 workers exposed to the risk of lead (work with lead containing glazing and prints). The lead concentration in the atmosphere did not exceed the highest permissible concentrations and the biological exposure tests as regards lead exposure did not exceed the highest permissible limits. In the examined subjects the authors found a significantly elevated level of superoxide dismutase activity (p < 0.05) which suggests long-term increased peroxide formation. The correlation of the selenium concentration in blood and the period of lead exposure was at the borderline of statistical significance (p = 0.1159). Further investigations will be focused on subjects with symptoms of increased exposure to lead and lead intoxication where the probability of pathological findings is greater.

[Significance of free radicals in the pathogenesis of rheumatic diseases and possibilities of decreasing their pathogenic effects]. / Význam volných radikálu v patogenezi revmatických chorob a moznosti snízení jejich patogenního pusobení.

The authors present the result of their work where they provide evidence that in inflammatory and degenerative diseases the break-down on superoxide in inadequate. This oxygen radicals and its metabolites play a significant role in the pathogenesis of these diseases. The authors revealed a severe defect in superoxide degeneration in particular in articular exudates of patients with active synovitis. Administration of the preparation Selzink-Plus of PRO.MED.CS Co. Prague which contains selenium, zinc, beta-cyrotene, vitamin C and E along with antirheumatic treatment improves according to the authors the breakdown of superoxide and its metabolites and improves thus the patient's prognosis. Long-term administration of the preparation seems to produce even better results.

[The effect of antioxidant therapy on indicators of activity of free radicals in workers exposed to risks of styrene]. / Ovlivnení ukazatelu pusobení volných radikálu u pracovníku z rizika styrenu antioxidacní lécbou.

To 30 workers exposed to the risk of styrene for a period of 30 days a mixture of antioxidants was administered: vitamin C 200 mg, vitamin E 300 mg, selenium 20 mg, troxerutin 600 mg and beta-carotene 6 mg. Before the onset of supplementation and immediately afterwards laboratory indicators of antioxidant protection and lipid peroxidation were investigated. Before treatment workers exposed to the risk of styrene had a significantly higher malondialdehyde concentration (p < 0.01) and antioxidant capacity (p < 0.01) as compared with the control group. Due to the established positive correlation between these parameters (r = 0.42, p < 0.05) the findings can be evaluated as the result of increased exposure to free radicals. After supplementation a marked decline of the malondialdehyde concentration occurred p < 0.001) and a further rise of the antioxidant capacity (p < 0.001). The selenium concentration increased also markedly, the rise being more marked in subjects who had originally a lower concentration. There was a significant rise of uric acid which has an antioxidant effect (p < 0.01). The antioxidant enzymes superoxide dismutase and gluathione peroxidase did not change significantly. The results indicate the favourable effect of antioxidant treatment in subjects exposed to the risk of styrene.

Influence of antioxidants on the quality of stored blood.

BACKGROUND AND OBJECTIVES: Blood is exposed to oxidation stress and therefore has a high antioxidant capacity (AOC). With the many factors increasing the demands on the AOC, there may be damage to erythrocytes by free radicals. This study was to investigate evidence of erythrocyte damage in stored donor blood and to affect this by premedication of blood donors. MATERIALS AND METHODS: Blood samples of 15 healthy donors were collected in CPDA-1 solution and analyzed immediately, and then again after 10 days of incubation at 4 degrees C and 1 day of incubation at 37 degrees C. Prior to incubation, the following parameters were evaluated: Na+, K+, malondialdehyde (MDA), hemoglobin (Hb), AOC in the supernatant, superoxide dismutase (SOD) in erythrocytes, and glutathione peroxidase (GSHPx) in whole blood. Blood donors of group 1 were not given any drugs or vitamins before blood sampling. The same blood donors were then supplemented with the following daily doses of antioxidants for 10 days before the next blood sampling: 36 mg of beta-carotene, 300 mg of vitamin E, 200 mg of vitamin C, and 40 mg of selenium. RESULTS: The blood from donors of group 2 had a significantly smaller increase in MDA, K+, and Hb, and a smaller decrease in Na+ and AOC in the supernatant compared with that of group 1, while the activity of SOD and GSHPx did not change during blood storage. CONCLUSIONS: These results suggest that antioxidants given to blood donors can improve red cell storage parameters by reducing cell damage caused by free radicals.

[Does plasmapheresis affect the production of free radicals and the antioxidant system?]. / Ovlivnuje plazmaferéza produkci volných radikálu a antioxidacní systém?

BACKGROUND: Free radicals cause lipid peroxidation, damage cell membranes and DNA. At present attention is paid to the relationship between extracorporeal methods of blood clearance, free radicals and the antioxidant system. The objective of the present study was to ascertain the effect of membrane plasmapheresis (PF) on the antioxidant defence of the organism and whether it has an impact on lipid peroxidation. METHODS AND RESULTS: Patients with inflammatory polyneuropathy (n = 7), pemphigus (n = 1) and pulmonary fibrosis (n = 1) were subjected to 3 PF each (apparatus Fresenius 2008 PF, filter Plasmaflux P2S). The following were assessed: superoxide dismutase activity (SOD) in red blood cells, the antioxidant capacity (AOK) and malondialdehyde (MDA) in plasma, glutathione peroxidase (GSHPx and selenium (Se) in blood, AOK, MDA and Se in the filtrate. The values were compared with those of 43 healthy volunteers using the t-test, changes of parameters during PF, using Wilcoxon's paired test. The baseline SOD, GSHPx, AOK and MDA values of patients did not differ from those of controls. SOD did not change in the course of PF. GSHPx declined during the 30th minute of PF and after PF (44.3 +/- 16.9 U/g, haemoglobin before vs. 37.5 +/- 12.2 during the 30th minute, p < 0.01, 36.7 +/- 14.6 after PF, p < 0.01). AOK rose during the 30th minute (p < 0.01) and after PF (p < 0.01). MDA after PF declined (p < 0.05). The baseline Se was higher than in controls (132.9 +/- 43.2 micrograms/l vs. 90.5 +/- 17.3, p < 0.01), after PF Se declined (100.1 +/- 28.3, p < 0.01). CONCLUSIONS: The authors did not provide evidence of increased lipid peroxidation during PF. During PF the GSHPx activity declines, most probably due to Se losses. The decline of GSHPx involves the risk of deterioration of hydrogen peroxide elimination and of increased free radical formation.

[Determination of free radical activity in workers at risk for styrene exposure]. / Stanovení úcinku volných radikálu u pracovnku v riziku styrenu.

The authors examined indicators of the effect of free radicals (MDA, SOD, GSHPx, selenium) in 38 workers exposed to styrene. They revealed a statistically significant (p < 0.01) correlation of SOD activity and the period of exposure to styrene and also a statistically significant correlation (p < 0.05) between urinary selenium excretion and the period of exposure to styrene as well as a statistically significant correlation (p < 0.01) between the MDA serum concentration and urinary selenium excretion. There is no statistically significant difference between the MDA plasma concentration among smokers and non-smokers, the SOD activity is significantly higher in non-smokers (p < 0.05). Based on the revealed findings the authors assume that free radicals may also play a part in the action of styrene on the organism.

[Lipid peroxidation and the antioxidant system in bicarbonate hemodialysis and acetate-free biofiltration]. / Peroxidace lipidu a antioxidacní systém pri bikarbonátové hemodialýze a bezacetátové biofiltraci.

Acetate-free biofiltration (AFB) is a modern haemodiafiltration method used at present as a variant in treatment of chronic renal failure. In AFB and standard bicarbonate haemodialysis (BHD), performed under equal conditions in 20 patients with chronic renal failure the authors investigated the degree of lipid peroxidation and the antioxidant defence system. As a marker of lipid peroxidation they used malondialdehyde (MDA); as to antioxidant factors they investigated the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSHP) in red blood cells and the selenium (Se) concentration in blood. The MDA values were elevated in both dialyzation methods, as compared with 30 healthy controls (p < 0.001). The SOD value before AFB did not differ from controls, before BHD it was higher than in controls (p < 0.01). In the course of AFB or BHD the SOD values did not change. The GSHPx activity at the end of AFB rose significantly as compared with the initial value (p < 0.05) and the value during the 30th minute of AFB (p < 0.02). In BHD the GSHPx activity was lower than in controls and did not change during the procedure (p < 0.01). The selenium blood levels were before both AFB and comparative BHD lower than in controls (p < 0.001). The authors found a positive correlation between the GSHPx activity and the Se level. The rise of GSHPx activity at the end of AFB may imply improved antioxidant defence during AFB and contribute to reduced tissue damage by free radicals.

[Administration of multivitamin combinations and trace elements in diabetes]. / Význam podávání multivitaminové smesi a stopových prvku u diabetu.

BACKGROUND: Many free radicals are formed in diabetes mellitus due to the oxidative stress in hyperglykemia. The objective of the investigation was to evaluate the influence of an antioxidant mixture and trace elements on some biochemical parameters in controls and diabetic patients. METHODS AND RESULTS: 13 controls (6 men and 7 women, the average age was 53 years) and 9 diabetic patients (4 men and 5 women, the average age was 52 years) were supplemented with multivitamin mixture and trace elements with respect to antioxidant activities. Both groups received the same amount of the mixture, controls 50 days, diabetic patients 35 days. Blood samples were measured before and after the treatment. Renal, liver tests and acid-base balance were not influenced. Apolipoprotein A increased significantly (p < 0.05). Glycosylated hemoglobin in the diabetic group decreased significantly from 9.4 +/- 1.6 to 7.2 +/- 1.5 mumol fructose/g of hemoglobin (p < 0.01). In the diabetic group increased the levels of ionorganic phosphorus from 0.99 +/- 0.08 to 1.15 +/- 0.13 mmol/L (p < 0.01), zinc from 10.4 +/- 1.3 to 14.3 +/- 1.7 mumol/L (p < 0.01), copper from 20.3 +/- 2.3 to 25.9 +/- 6.3 mumol/L (p < 0.05) and selenium in blood from 0.96 +/- 0.21 to 1.65 +/- 0.38 mumol/L (p < 0.001). Selenium in blood of the control group increased from 0.88 +/- 0.26 to 1.66 +/- 0.34 mumol/L (p < 0.001). The activity of superoxide dismutase (SOD) in diabetic group increased from 598 +/- 105 to 696 +/- 103 U/g of hemoglobin (p < 0.01), the activity of glutathion peroxidase (GSHPx) did not change, malondialdehyde (MDA) decreased from 7.1 +/- 1.1 to 5.8 +/- 1.1 mumol/L (p < 0.01) and uric acid decreased from 261 +/- 83 to 236 +/- 96 mumol/L (p < 0.01). CONCLUSIONS: Multivitamin mixture with trace elements significantly protects diabetic patients and the control group against injurous actions of free radicals. That is confirmed by the decrease of plasmatic malondialdehyde and uric acid and by the increase of superoxide dismutase in erythrocytes. The decrease of glycosylated hemoglobin reduces the probability of diabetic complications, the increase of plasmatic Zn and Se in the diabetic group increased the plasmatic antioxidant ability.