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Biomedical subjects

V Holecek

Publications and source records attributed to V Holecek.

At least 19 recordsLinked to original sources
PubMed2002

[Free radicals and antioxidants in cerebrospinal fluid in central nervous system diseases].

Free radicals and antioxidants may play a role in the etiology and pathogenesis of some central nervous diseases. The brain tissue is relatively insufficiently protected by antioxidants against the free radical induced damage. The brain situation may be reflected by the cerebrospinal fluid examination, which has not enough attention. It seems, that from this point of view subarachnoical hemorrhagy, meningitis, hydrocephalus, Alzheimer's, Parkinson's and Huntington's diseases, multiple sclerosis and probably schizophrenia should receive a special attention.

Antioxidants↗
PubMed2001

[Free radicals in immunology and infectious diseases].

Free radicals contribute significantly in modification of immune processes and inflammatory reactions. They are produced by activated phagocytes which use them for killing microorganisms. Free radicals facilitate production of cytokines, which are important as modifiers of inflammatory reactions. Formation of free radicals is influenced by antioxidants which can thus modify the intensity of inflammatory reaction and immune response. The authors describe in detail the contribution of free radicals in etiology and pathogenesis of autoimmune diseases including rheumatoid arthritis, multiple sclerosis or amyotrophic lateral sclerosis. The role of free radicals and modifying influence of antioxidants in viral, bacterial, parasitic and mycotic diseases is described in the second part of the review. Finally, influence of free radicals and antioxidants on immunity changes in patients with malignant tumours, during aging and physical exercise is discussed.

Aging↗
PubMed2001

[Antioxidant effects of melatonin].

Increase in knowledge about reactive oxygen species action mechanisms and oxidative stress effects in living organisms led to intensive seeking for new, more effective substances, which prevent extreme development of oxidative stress or are able to decrease its negative influence, damaging cell structures and many cell functions. These substances are called antioxidants, scavengers, trappers or quenchers. In nineties, melatonin became the centre of the interest in the filed of investigation of antioxidative properties of different chemical substances. This is in living organisms ubiquitous substance with relatively simple chemical structure, good physical properties and wide physiological effects. The main role of endogenous melatonin comprises receptor-mediated biological rhythms synchronisation. Among other functions mentioned later belong anti-gonadotropic, immunotropic and non-receptor-mediated antioxidative effects. Melatonin is said to have also antineoplastic properties. Its anti-aging effect is discutable.

Analgesics↗
PubMed2001

What is the source of free radicals causing hemolysis in stored blood?

The quality of stored blood can be deteriorated by hemolysis caused by free radicals. The purpose of this study was to elucidate whether neutrophile leukocytes are the source of free radicals in stored blood as in hemodialyzed patients. Resuspensions with low (LL) or high (HL) leukocyte concentrations were prepared from samples of twenty healthy volunteers. The samples were incubated for 10 days at 4 degrees C and then for one day at 37 degrees C. Markers of hemolysis and free radical metabolism were examined before and after incubation in LL and HL samples. In spite of the difference of leukocytes counts in LL and HL resuspensions (p<0.0001), the pre-incubation values of all laboratory parameters were practically identical. In post-storage samples, superoxide dismutase and glutathione peroxidase activities did not differ in either group. Reduced glutathione in erythrocytes and extracellular antioxidant capacity were insignificantly lower in HL resuspensions, but the increase of malondialdehyde was much more pronounced in the HL samples (p<0.0001). The degree of hemolysis, expressed as the extracellular increase of potassium (p<0.001), hemoglobin (p<0.05) and lactate dehydrogenase (p<0.05), was higher in the HL samples. Our results support the hypothesis that leukocytes participate in free radical production in stored blood.

Antioxidants↗
PubMed2001

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.

Animals↗
PubMed2000

[Antioxidative properties of ascorbic acid].

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.

Animals↗
PubMed2000

[Antioxidants and protection of the skin against the effect of ultraviolet rays].

Ultraviolet radiation causes increase of production of the reactive oxygen species in the human skin, which are responsible for oxidative stress and damage of many important cellular components in the target tissue. The complex of antioxidants represents the major protective system against the oxidative damage of the skin. Many antioxidants, namely vitamin E, can be successfully used in photoprotection.

Antioxidants↗
PubMed2000

Anticipation of acute stress in isoprenaline-sensitive and - resistant rats: strain and gender differences.

The effect of stress anticipation was studied in two inbred Wistar rat strains with high and low sensitivity to isoprenaline. The animals were exposed to tail-flick and 4-hr water immersion restraint stress on two consecutive days. On the first day stress was applied to one group and the next day to the anticipation group. The changes in adrenal, heart and spleen weights, tail-flick latency, incidence of gastric ulcers, and the antioxidant defense system in the sensorimotor cortex were compared with two non-stressed control groups. Anticipatory stress decreased adrenal weights. The content of thiobarbituric acid reactive substances (TBARS) was increased both in acute and anticipatory stress; superoxide dismutase, glutathione peroxidase, and antioxidative capacity were increased in anticipatory stress only. Stress anticipation decreased the pain threshold in the isoprenaline-sensitive and increased in the isoprenaline-resistant rats and led to more frequent gastric ulcers in the isoprenaline-resistant group. Significant sex differences were observed both in adrenal weights and TBARS content. The relative adrenal weights were negatively correlated with the TBARS content. We suggest that the outcome of anticipatory stress may depend upon the relation between the hormonal and antioxidant functions of the adrenals and that anticipation-induced activation of antioxidant enzymes may ameliorate the acute stress response. Anticipation itself was found to be a stronger stressor than physical acute stress.

Analysis of Variance↗
PubMed1999

[Indicators of oxidative stress in cardiovascular diseases. I. Lipoperoxidation].

The level od malondialdehyde (MDA), thiobarbituric acid reactive substances (TBARS) respectively, in blood is changing very quickly and therefore isoprostanes scam to be better markers of atherogenesis. Oxidized LDL belong to the most important reasons of the origin of foam cells and therefore of atherogenesis. That is why the inhibition of the oxidation of LDL particles should belong to the standard therapy of cardiovascular diseases. The value of antibodies against oxidized LDL is difficult to interpret, because they are multifactor dependent, especially under genetic control. Antibodies against LDL modified by malondialdehyde (MDA-LDL) are increased in smokers and individuals with a rapid atherosclerotic progression. HDL-cholesterol protects LDL through the oxidized lipid exchange. Oxidized HDL formed during this process has then an increased clearance from circulation.

Cardiovascular Diseases↗
PubMed1999

[Indicators of oxidative stress in cardiovascular diseases. II. Nitrogenous substances, AGE-substances and antioxidants].

By oxidation of nitrogen oxide nitrites and nitrates are formed which can be considered markers of inflammation. AGE-substances (products of advanced glycation) are formed not only from proteins (e.g. Hb-AGE) but also from lipids (AGE-LDL) and DNA (AGE-DNA) and lead to an increased number of mutations. They are toxic and are deposited in the vascular wall. They cause coagulopathy, stimulate cytokines and inactivate nitrogen oxide and thus prevent relaxation of the vascular wall. Extracellular superoxide dismutase (EC-SOD) has a variant (mutation Arg213Gly with a 4% incidence) which causes deterioration of the cardiac prognosis. Selenium deficiency leads also to an increased frequency of cardiovascular diseases.

Antioxidants↗
PubMed1998

[Significance of free radicals in the pathogenesis of rheumatic diseases and possibilities of decreasing their pathogenic effects].

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.

Arthritis↗
PubMed1998

[Indicators of effects of free radicals in workers at risk of lead exposure].

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.

Adult↗
PubMed1997

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.

Antioxidants↗
PubMed1997

[The effect of antioxidant therapy on indicators of activity of free radicals in workers exposed to risks of styrene].

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.

Adult↗
PubMed1996

[Antioxidants and malondialdehyde during hemodialysis with cellulose diacetate and polysulfone membranes].

BACKGROUND: Free radicals (FR) may cause lipid peroxidation and damage macromolecules and cellular structure of the organism, e.g. endothelium and erythrocytes. Some studies have shown that haemodialysis is connected with increased FR production. The aim of the study was to evaluate the effects of two dialysis membranes on lipid peroxidation and some antioxidant protective factors. METHODS AND RESULTS: The authors followed nine patients treated in a regular dialysis programme. In a cross controlled study the patients underwent haemodialysis with the use of cellulose diacetate (CDA) and polysulfone (PS) dialysis apparatus. Malondialdehyde in plasma was determined as a marker of lipid peroxidation. The haemodialysis with CDA or PS did not result in increased malondialdehyde levels in min. 30 or at the end of the procedure. The antioxidant capacity of plasma decreased after haemodialysis in a similar way with both types of membranes (PS, 1.67 +/- 0.10 mumol/l versus 1.47 +/- 0.23, P < 0.05; CDA: 1.72 +/- 0.10 versus 1.55 +/- 0.12, P < 0.05). The selenium blood level did not change. Activity of glutathione peroxidase (GSHPx) in blood before the dialysis was higher in the observation with subsequent use of CDA than while using PS (38.6 +/- 9.4 versus 34.5 +/- 6.6, P < 0.05). In the cohort with polysulfone membrane GSHPx further decreased in min. 30 of haemodialysis (34.0 +/- 6.6 IU/g Hb versus 31.1 +/- 5.0, P < 0.05). Superoxide dismutase (SOD) was also higher in dialysis with CDA membrane that while using PS (846 +/- 171 IU/g Hb versus 522 +/- 141, P < 0.05). CONCLUSIONS: The activity of antioxidant enzymes GSHPx and SOD was lower with polysulfone membrane than with the cellulose acetate membrane. GSHPx activity also further decreased from min. 30 of dialysis with the PS membrane. It may be due to increased production of superoxide anion and hydrogen peroxide during haemodialysis with the PS. Lipid peroxidation has not been proved to increase during haemodialysis with the CDA or PS membrane.

Adult↗
PubMed1996

[Does plasmapheresis affect the production of free radicals and the antioxidant system?].

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.

Antioxidants↗